If the standard deviation of the mean for the sampling distribution of random samples of size 36 from a large or infinite population is 2, how large must the sample size become if the standard deviation is to be reduced to 1.2?
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Standard deviation (Error) of the mean = Standard deviation of the population / sqrt sample size
Let the standard deviation of the population = x
2 = x / sqrt 36
2 = x/6
x = 12
If the standard error is to be reduced to 1.2
1.2 = 12 / sqrt n
sqrt n = 12/1.2 = 10
n = 10^2 = 100
Sample size must be = 100 if the standard error is to be reduced to 1.2
Let the standard deviation of the population = x
2 = x / sqrt 36
2 = x/6
x = 12
If the standard error is to be reduced to 1.2
1.2 = 12 / sqrt n
sqrt n = 12/1.2 = 10
n = 10^2 = 100
Sample size must be = 100 if the standard error is to be reduced to 1.2
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