Mathematics 10 — Exercise 11.1 · Q1 (i–ii)

Full question

The table gives the scores in a memory test, in classes 44–48, 49–53, 54–58, 59–63, 64–68, 69–73 and 74–78. Draw a cumulative-frequency graph. Use it to estimate the median, first and third quartiles Q₁ and Q₃, third decile D₃, 90th percentile P₉₀ and interquartile range. Give answers to the nearest whole number.

Score intervalFrequency
44–483
49–5312
54–5815
59–6323
64–6812
69–738
74–787

Step-by-step solution

  1. The scores are whole numbers. Convert each interval to continuous boundaries by subtracting 0.5 from its lower limit and adding 0.5 to its upper limit:44–48 becomes 43.5–48.5,49–53 becomes 48.5–53.5, and so on.

  2. Cumulative frequency means a running total. Begin with zero at the first lower boundary.

  3. Class 87/2–97/2: add frequency 3 to the preceding total.

    0+3=3
  4. Class 97/2–107/2: add frequency 12 to the preceding total.

    3+12=15
  5. Class 107/2–117/2: add frequency 15 to the preceding total.

    15+15=30
  6. Class 117/2–127/2: add frequency 23 to the preceding total.

    30+23=53
  7. Class 127/2–137/2: add frequency 12 to the preceding total.

    53+12=65
  8. Class 137/2–147/2: add frequency 8 to the preceding total.

    65+8=73
  9. Class 147/2–157/2: add frequency 7 to the preceding total.

    73+7=80
  10. Plot each UPPER boundary against its cumulative frequency, and join adjacent points.

  11. Median: find the cumulative-frequency position 1/2×80.

    12×80=40
  12. Calculate this operation before combining the remaining terms.

    (-1)×30=-30
  13. For multiplication of fractions, multiply the numerators together and the denominators together.

    117×11×2
  14. Calculate these two products separately.

    1172
  15. Calculate this operation before combining the remaining terms.

    117×12=1172
  16. Keep the common denominator and add the signed numerators.

    100+269146=279146
  17. Calculate this operation before combining the remaining terms.

    5023+1172=279146
  18. Median lies between cumulative totals 30 and 53. Interpolate along that graph segment: lower boundary + (position−previous total)/class frequency × class width.

    40−3023×5+1172
  19. Calculate this operation before combining the remaining terms.

    40−30=10
  20. Calculate this operation before combining the remaining terms.

    10×1=10
  21. Calculate this operation before combining the remaining terms.

    1×23=23
  22. For multiplication of fractions, multiply the numerators together and the denominators together.

    10×11×23
  23. Calculate these two products separately.

    1023
  24. For multiplication of fractions, multiply the numerators together and the denominators together.

    1×11×23
  25. Calculate these two products separately.

    123
  26. Calculate this operation before combining the remaining terms.

    1×123=123
  27. Calculate this operation before combining the remaining terms.

    10×123=1023
  28. Calculate this operation before combining the remaining terms.

    10×5=50
  29. Calculate this operation before combining the remaining terms.

    23×1=23
  30. For multiplication of fractions, multiply the numerators together and the denominators together.

    50×11×23
  31. Calculate this operation before combining the remaining terms.

    50×123=5023
  32. For multiplication of fractions, multiply the numerators together and the denominators together.

    10×523×1
  33. Calculate these two products separately.

    5023
  34. Calculate this operation before combining the remaining terms.

    1023×5=5023
  35. To add these fractions, first use a common denominator: the least common multiple of their denominators.

    LCD=46
  36. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    1172=117×232×23
  37. Calculate the converted numerator; the denominator is now common.

    269146
  38. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    5023=50×223×2
  39. Calculate the converted numerator; the denominator is now common.

    10046
  40. Calculate this operation before combining the remaining terms.

    2691+100=2791
  41. For multiplication of fractions, multiply the numerators together and the denominators together.

    2791×11×46
  42. Calculate these two products separately.

    279146
  43. Calculate this operation before combining the remaining terms.

    2791×146=279146
  44. Keep the common denominator and add the signed numerators.

    2691+10046=279146
  45. Calculate this operation before combining the remaining terms.

    1172+5023=279146
  46. Median ≈ 60.674, rounded to a whole number: 61.

    279146
  47. Q1: find the cumulative-frequency position 1/4×80.

    14×80=20
  48. Calculate this operation before combining the remaining terms.

    (-1)×15=-15
  49. For multiplication of fractions, multiply the numerators together and the denominators together.

    107×11×2
  50. Calculate this operation before combining the remaining terms.

    107×12=1072
  51. Keep the common denominator and add the signed numerators.

    10+3216=3316
  52. Calculate this operation before combining the remaining terms.

    53+1072=3316
  53. Q1 lies between cumulative totals 15 and 30. Interpolate along that graph segment: lower boundary + (position−previous total)/class frequency × class width.

    20−1515×5+1072
  54. Calculate this operation before combining the remaining terms.

    20−15=5
  55. Calculate this operation before combining the remaining terms.

    5×1=5
  56. Calculate this operation before combining the remaining terms.

    1×15=15
  57. For multiplication of fractions, multiply the numerators together and the denominators together.

    5×11×15
  58. Calculate these two products separately.

    515
  59. The numerator and denominator have this greatest common divisor. Divide BOTH by it.

    GCD=5
  60. For multiplication of fractions, multiply the numerators together and the denominators together.

    5×11×5
  61. Calculate these two products separately.

    55
  62. Show the two divisions explicitly.

    5555
  63. Write the reduced fraction.

    11
  64. Calculate this operation before combining the remaining terms.

    5×15=1
  65. For multiplication of fractions, multiply the numerators together and the denominators together.

    15×11×5
  66. Calculate this operation before combining the remaining terms.

    15×15=3
  67. For multiplication of fractions, multiply the numerators together and the denominators together.

    1×11×3
  68. Calculate this operation before combining the remaining terms.

    1×13=13
  69. Show the two divisions explicitly.

    55155
  70. Evaluate the numerator division.

    55=1
  71. Evaluate the denominator division.

    155=3
  72. Write the reduced fraction.

    13
  73. For multiplication of fractions, multiply the numerators together and the denominators together.

    1×11×15
  74. Calculate these two products separately.

    115
  75. Calculate this operation before combining the remaining terms.

    1×115=115
  76. Calculate this operation before combining the remaining terms.

    5×115=13
  77. Calculate this operation before combining the remaining terms.

    1×5=5
  78. Calculate this operation before combining the remaining terms.

    3×1=3
  79. For multiplication of fractions, multiply the numerators together and the denominators together.

    5×11×3
  80. Calculate this operation before combining the remaining terms.

    5×13=53
  81. For multiplication of fractions, multiply the numerators together and the denominators together.

    1×53×1
  82. Calculate these two products separately.

    53
  83. Calculate this operation before combining the remaining terms.

    13×5=53
  84. To add these fractions, first use a common denominator: the least common multiple of their denominators.

    LCD=6
  85. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    1072=107×32×3
  86. Calculate the converted numerator; the denominator is now common.

    3216
  87. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    53=5×23×2
  88. Calculate the converted numerator; the denominator is now common.

    106
  89. Calculate this operation before combining the remaining terms.

    321+10=331
  90. For multiplication of fractions, multiply the numerators together and the denominators together.

    331×11×6
  91. Calculate these two products separately.

    3316
  92. Calculate this operation before combining the remaining terms.

    331×16=3316
  93. Keep the common denominator and add the signed numerators.

    321+106=3316
  94. Calculate this operation before combining the remaining terms.

    1072+53=3316
  95. Q1 ≈ 55.167, rounded to a whole number: 55.

    3316
  96. Q3: find the cumulative-frequency position 3/4×80.

    34×80=60
  97. Calculate this operation before combining the remaining terms.

    (-1)×53=-53
  98. For multiplication of fractions, multiply the numerators together and the denominators together.

    127×11×2
  99. Calculate these two products separately.

    1272
  100. Calculate this operation before combining the remaining terms.

    127×12=1272
  101. Keep the common denominator and add the signed numerators.

    35+76212=79712
  102. Calculate this operation before combining the remaining terms.

    3512+1272=79712
  103. Q3 lies between cumulative totals 53 and 65. Interpolate along that graph segment: lower boundary + (position−previous total)/class frequency × class width.

    60−5312×5+1272
  104. Calculate this operation before combining the remaining terms.

    60−53=7
  105. Calculate this operation before combining the remaining terms.

    7×1=7
  106. Calculate this operation before combining the remaining terms.

    1×12=12
  107. For multiplication of fractions, multiply the numerators together and the denominators together.

    7×11×12
  108. Calculate these two products separately.

    712
  109. For multiplication of fractions, multiply the numerators together and the denominators together.

    1×11×12
  110. Calculate these two products separately.

    112
  111. Calculate this operation before combining the remaining terms.

    1×112=112
  112. Calculate this operation before combining the remaining terms.

    7×112=712
  113. Calculate this operation before combining the remaining terms.

    7×5=35
  114. Calculate this operation before combining the remaining terms.

    12×1=12
  115. For multiplication of fractions, multiply the numerators together and the denominators together.

    35×11×12
  116. Calculate this operation before combining the remaining terms.

    35×112=3512
  117. For multiplication of fractions, multiply the numerators together and the denominators together.

    7×512×1
  118. Calculate these two products separately.

    3512
  119. Calculate this operation before combining the remaining terms.

    712×5=3512
  120. To add these fractions, first use a common denominator: the least common multiple of their denominators.

    LCD=12
  121. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    1272=127×62×6
  122. Calculate the converted numerator; the denominator is now common.

    76212
  123. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    3512=35×112×1
  124. Calculate the converted numerator; the denominator is now common.

    3512
  125. Calculate this operation before combining the remaining terms.

    762+35=797
  126. For multiplication of fractions, multiply the numerators together and the denominators together.

    797×11×12
  127. Calculate this operation before combining the remaining terms.

    797×112=79712
  128. Keep the common denominator and add the signed numerators.

    762+3512=79712
  129. Calculate this operation before combining the remaining terms.

    1272+3512=79712
  130. Q3 ≈ 66.417, rounded to a whole number: 66.

    79712
  131. D3: find the cumulative-frequency position 3/10×80.

    310×80=24
  132. Keep the common denominator and add the signed numerators.

    6+1072=1132
  133. Calculate this operation before combining the remaining terms.

    3+1072=1132
  134. D3 lies between cumulative totals 15 and 30. Interpolate along that graph segment: lower boundary + (position−previous total)/class frequency × class width.

    24−1515×5+1072
  135. Calculate this operation before combining the remaining terms.

    24−15=9
  136. Calculate this operation before combining the remaining terms.

    9×1=9
  137. For multiplication of fractions, multiply the numerators together and the denominators together.

    9×11×15
  138. Calculate these two products separately.

    915
  139. The numerator and denominator have this greatest common divisor. Divide BOTH by it.

    GCD=3
  140. For multiplication of fractions, multiply the numerators together and the denominators together.

    9×11×3
  141. Calculate these two products separately.

    93
  142. Show the two divisions explicitly.

    9333
  143. Evaluate the denominator division.

    33=1
  144. Calculate this operation before combining the remaining terms.

    9×13=3
  145. For multiplication of fractions, multiply the numerators together and the denominators together.

    15×11×3
  146. Calculate these two products separately.

    153
  147. Show the two divisions explicitly.

    15333
  148. Write the reduced fraction.

    5×11
  149. Calculate this operation before combining the remaining terms.

    15×13=5
  150. For multiplication of fractions, multiply the numerators together and the denominators together.

    3×11×5
  151. Calculate this operation before combining the remaining terms.

    3×15=35
  152. Show the two divisions explicitly.

    93153
  153. Evaluate the numerator division.

    93=3
  154. Evaluate the denominator division.

    153=5
  155. Write the reduced fraction.

    35
  156. Calculate this operation before combining the remaining terms.

    9×115=35
  157. Calculate this operation before combining the remaining terms.

    3×5=15
  158. For multiplication of fractions, multiply the numerators together and the denominators together.

    3×55×1
  159. Calculate these two products separately.

    155
  160. The numerator and denominator have this greatest common divisor. Divide BOTH by it.

    GCD=5
  161. Calculate this operation before combining the remaining terms.

    11=1
  162. Show the two divisions explicitly.

    15555
  163. Evaluate the numerator division.

    155=3
  164. Evaluate the denominator division.

    55=1
  165. Write the reduced fraction.

    3×11
  166. Calculate this operation before combining the remaining terms.

    35×5=3
  167. To add these fractions, first use a common denominator: the least common multiple of their denominators.

    LCD=2
  168. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    1072=107×12×1
  169. Calculate the converted numerator; the denominator is now common.

    1072
  170. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    3×11=3×21×2
  171. Calculate the converted numerator; the denominator is now common.

    62
  172. Calculate this operation before combining the remaining terms.

    107+6=113
  173. For multiplication of fractions, multiply the numerators together and the denominators together.

    113×11×2
  174. Calculate these two products separately.

    1132
  175. Calculate this operation before combining the remaining terms.

    113×12=1132
  176. Keep the common denominator and add the signed numerators.

    107+62=1132
  177. Calculate this operation before combining the remaining terms.

    1072+3=1132
  178. D3 ≈ 56.500, rounded to a whole number: 57.

    1132
  179. P90: find the cumulative-frequency position 9/10×80.

    910×80=72
  180. Calculate this operation before combining the remaining terms.

    (-1)×65=-65
  181. For multiplication of fractions, multiply the numerators together and the denominators together.

    137×11×2
  182. Calculate these two products separately.

    1372
  183. Calculate this operation before combining the remaining terms.

    137×12=1372
  184. Keep the common denominator and add the signed numerators.

    35+5488=5838
  185. Calculate this operation before combining the remaining terms.

    358+1372=5838
  186. P90 lies between cumulative totals 65 and 73. Interpolate along that graph segment: lower boundary + (position−previous total)/class frequency × class width.

    72−658×5+1372
  187. Calculate this operation before combining the remaining terms.

    72−65=7
  188. Calculate this operation before combining the remaining terms.

    1×8=8
  189. For multiplication of fractions, multiply the numerators together and the denominators together.

    7×11×8
  190. Calculate these two products separately.

    78
  191. For multiplication of fractions, multiply the numerators together and the denominators together.

    1×11×8
  192. Calculate these two products separately.

    18
  193. Calculate this operation before combining the remaining terms.

    1×18=18
  194. Calculate this operation before combining the remaining terms.

    7×18=78
  195. Calculate this operation before combining the remaining terms.

    8×1=8
  196. For multiplication of fractions, multiply the numerators together and the denominators together.

    35×11×8
  197. Calculate this operation before combining the remaining terms.

    35×18=358
  198. For multiplication of fractions, multiply the numerators together and the denominators together.

    7×58×1
  199. Calculate these two products separately.

    358
  200. Calculate this operation before combining the remaining terms.

    78×5=358
  201. To add these fractions, first use a common denominator: the least common multiple of their denominators.

    LCD=8
  202. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    1372=137×42×4
  203. Calculate the converted numerator; the denominator is now common.

    5488
  204. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    358=35×18×1
  205. Calculate the converted numerator; the denominator is now common.

    358
  206. Calculate this operation before combining the remaining terms.

    548+35=583
  207. For multiplication of fractions, multiply the numerators together and the denominators together.

    583×11×8
  208. Calculate these two products separately.

    5838
  209. Calculate this operation before combining the remaining terms.

    583×18=5838
  210. Keep the common denominator and add the signed numerators.

    548+358=5838
  211. Calculate this operation before combining the remaining terms.

    1372+358=5838
  212. P90 ≈ 72.875, rounded to a whole number: 73.

    5838
  213. For multiplication of fractions, multiply the numerators together and the denominators together.

    (-1)×3311×6
  214. Calculate these two products separately.

    -3316
  215. Calculate this operation before combining the remaining terms.

    (-1)×3316=-3316
  216. Interquartile range is Q3−Q1.

    79712−3316
  217. To add these fractions, first use a common denominator: the least common multiple of their denominators.

    LCD=12
  218. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    79712=797×112×1
  219. Calculate the converted numerator; the denominator is now common.

    79712
  220. For multiplication of fractions, multiply the numerators together and the denominators together.

    (-331)×11×6
  221. Calculate this operation before combining the remaining terms.

    (-331)×16=-3316
  222. Multiply this numerator AND denominator by the same factor. Its value stays unchanged.

    -3316=(-331)×26×2
  223. For multiplication of fractions, multiply the numerators together and the denominators together.

    (-662)×11×12
  224. The numerator and denominator have this greatest common divisor. Divide BOTH by it.

    GCD=2
  225. Show the two divisions explicitly.

    -6622122
  226. Evaluate the numerator division.

    -6622=-331
  227. Evaluate the denominator division.

    122=6
  228. Calculate this operation before combining the remaining terms.

    (-662)×112=-3316
  229. Calculate the converted numerator; the denominator is now common.

    -66212
  230. Calculate this operation before combining the remaining terms.

    (-1)×662=-662
  231. Calculate this operation before combining the remaining terms.

    797−662=135
  232. For multiplication of fractions, multiply the numerators together and the denominators together.

    135×11×12
  233. Calculate these two products separately.

    13512
  234. Calculate this operation before combining the remaining terms.

    135×112=454
  235. Keep the common denominator and add the signed numerators.

    797−66212=13512
  236. The numerator and denominator have this greatest common divisor. Divide BOTH by it.

    GCD=3
  237. For multiplication of fractions, multiply the numerators together and the denominators together.

    135×11×3
  238. Calculate these two products separately.

    1353
  239. Show the two divisions explicitly.

    135333
  240. Write the reduced fraction.

    45×11
  241. Calculate this operation before combining the remaining terms.

    135×13=45
  242. For multiplication of fractions, multiply the numerators together and the denominators together.

    12×11×3
  243. Calculate these two products separately.

    123
  244. Show the two divisions explicitly.

    12333
  245. Write the reduced fraction.

    4×11
  246. Calculate this operation before combining the remaining terms.

    12×13=4
  247. For multiplication of fractions, multiply the numerators together and the denominators together.

    45×11×4
  248. Calculate this operation before combining the remaining terms.

    45×14=454
  249. Show the two divisions explicitly.

    1353123
  250. Evaluate the numerator division.

    1353=45
  251. Evaluate the denominator division.

    123=4
  252. Write the reduced fraction.

    454
  253. Calculate this operation before combining the remaining terms.

    79712−3316=454
ClassfCumulative f
43.5–48.533
48.5–53.51215
53.5–58.51530
58.5–63.52353
63.5–68.51265
68.5–73.5873
73.5–78.5780

Answer

Median ≈ 61; Q1 ≈ 55; Q3 ≈ 66; D3 ≈ 57; P90 ≈ 73; IQR ≈ 11

43.50478.6450.517.35425.957.534.66143.264.551.86860.571.569.17577.878.586.4Median ≈ 60.67Q1 ≈ 55.17Q3 ≈ 66.42D3 ≈ 56.50P90 ≈ 72.88Score / valueCumulative frequency