Find the value of p, if the mean of the following distribution is 20
x: 15 17 19 20+p 23 f: 2 3 4 5p 6 |
note : the method should be of sigma fixi.
Mean = (sigma fixi)/ (sigma fi)
={ (2 X 15) + (3 X 17) + (4 X 19) + 5p(20 + p) + (6 X 23) } / (2 + 3 + 4 + 5p + 6)
= (295 + 100p + 5p2) / (15 + 5p)
= (59 + 20p + p2) / (3 + p)
Bt, mean = 20 ( given)
Therefore , (59 + 20p + p2) / ( 3 + p) = 20
=> 59 + 20p + p2 = 60 + 20p
=> p2 = 1
=> p =1