Question

9. The weight (in kg) of 50 contestants at a competition is as follows:
65 66 67 66 64 66 65 63 65 68, 64 62 66 64 67 65 64 66 65 67, 65 67 66 64 65 64 66 65 64 65, 66 65 64 63 67 63 65 63 67 64, 66 64 68 65 63 65 64 67 66 64
(a) Construct a frequency table for the discrete data.
(b) Calculate, correct to 2 decimal places, the (i) mean (ii) standard deviation of the data

Accepted Answer

(a) Frequency Table:
Weight(62): Tally 1, Frequency 1
Weight(63): Frequency 5
Weight(64): Frequency 12
Weight(65): Frequency 14
Weight(66): Frequency 10
Weight(67): Frequency 6
Weight(68): Frequency 2
Total = 50

(b)(i) Mean = Σfx/Σf = 3253/50 = 65.06kg (2 d.p.)

(ii) Standard deviation = √[(Σfx²/Σf) - (Σfx/Σf)²]
Σfx² = 211,733
= √[(211733/50) - (3253/50)²]
= √[4234.66 - 4232.80]
= √1.8364
= 1.36kg

WAEC Mathematics 2016 Theory — Question 9

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