Statistics, SPM Paper 1 (Short Questions)


Question 7:
A set of data consists of twelve positive numbers.
It is given that Σ ( x x ¯ ) 2 =600 and Σ x 2 =1032.
Find
(a) the variance
(b) the mean

Solution:
(a)
Variance= Σ ( x x ¯ ) 2 N               = 600 12               =50

(b)
Variance= Σ x 2 N ( x ¯ ) 2           50= 1032 12 ( x ¯ ) 2        ( x ¯ ) 2 =8650              =36             x ¯ =36

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