ECZ 2017 · O-Level Paper 2 · Question 8 — Statistics
The table below shows the amount of money spent by 100 learners at school on a particular day. Amount in Kwacha0<x≤55<x≤1010<x≤1515<x≤2020<x≤2525<x≤30Frequency1327351672
(a) Calculate the standard deviation.[6]
Verified working — step 1
Midpoints x: 2.5, 7.5, 12.5, 17.5, 22.5, 27.5 with f: 13, 27, 35, 16, 7, 2.(b(i)) Using the table above, copy and complete the cumulative frequency table. Amount in Kwacha≤0≤5≤10≤15≤20≤25≤30Frequency01340100[1]
Verified working — step 1
Add each frequency t…(b(ii)) Using a scale of 2 cm to represent 5 units on the horizontal axis and 2 cm to represent 10 units on the vertical axis, draw a smooth cumulative frequency curve.[3]
Verified working — step 1
Plot each upper class boundary against its cum…(b(iii)) Showing your method clearly, use your graph to estimate the semi-interquartile range.[2]
Verified working — step 1
n = 100, so read the lower quartile at cf = 25 and the upper quartile at cf = 75.The full step-by-step working and final answer are included with Premium — checked against ECZ marking standards.
Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.
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