ECZ 2016 · O-Level Paper 2 · Question 7 — Statistics
The ages of people living at Pamodzi Village are recorded in the frequency table below. Age0<x≤1010<x≤2020<x≤3030<x≤4040<x≤5050<x≤60Number of people7222823155
(a) Calculate the standard deviation.[6]
Verified working — step 1
Midpoints x: 5, 15, 25, 35, 45, 55 with frequencies f: 7, 22, 28, 23, 15, 5.(b(i)) Using the information in the table above, copy and complete the cumulative frequency table. Age≤10≤20≤30≤40≤50≤60Number of people729100[1]
Verified working — step 1
Add each frequency t…(b(ii)) Using a scale of 2 cm to represent 10 units on both axes, draw a smooth cumulative frequency curve where 0 <= x <= 60 and 0 <= y <= 100.[3]
Verified working — step 1
Plot each upper class boundary against its cumulative fre…(b(iii)) Showing your method clearly, use your graph to estimate the semi-interquartile range.[2]
Verified working — step 1
n = 100, so the lower quartile is read 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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