xbar 200 sigma 50 n 100 sigmaxbar PX

xbar 200 sigma 50 n 100 sigma-xbar P(X<205) P(X<195) Assume the population standard deviation is =25 Computethe standard error of the mean, xmean for sample sizes of 50, 100 150, 200. What can you say about the size of the standard error of the meanas the sample size is increased?

Solution

a) 50

SD = 25 / srqt (50) = 3.54

for 100

SD = 25 / srqt(100) = 2.5

for 150

SD = 25 / srqt (150) = 2.04

for 200

SD = 25 / srqt (200) = 1.77

if the sample size is increased we will say that the size of SD will decrease