Q16 of 33 Page 14

Find the value of p, if the mean of the following distribution is 20.

x: 15 17 19 20+p 23


y: 2 3 4 5p 6


Explanation:



Given,


Mean = 20





295 + 100p + 5p2 = 100p + 300


295 + 5p2 = 300


5p2 = 300 – 295


5p2 – 5 = 0


5 (p2 – 1) = 0


p2 – 1 = 0


(p + 1) (p – 1) = 0


p = ± 1


If p + 1 = 0, p = - 1 (Reject)


Or p – 1 = 0, p = 1


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