# Finding sample size

• Nov 12th 2011, 04:55 AM
blueberryhill
Finding sample size
i need to find the size of 2 samples based on this information

The population variance of the distribution for X is 100. 2 random samples of size n1 and n2 are repeatedly taken from the population. the sample means for sample size n1 and sample size n2 have the follwing distributions:

X ~ N(1,10)
X ~ N(1,2.5)
(X should be X with a bar over it)

• Nov 12th 2011, 06:09 AM
CaptainBlack
Re: Finding sample size
Quote:

Originally Posted by blueberryhill
i need to find the size of 2 samples based on this information

The population variance of the distribution for X is 100. 2 random samples of size n1 and n2 are repeatedly taken from the population. the sample means for sample size n1 and sample size n2 have the follwing distributions:

X ~ N(1,10)
X ~ N(1,2.5)
(X should be X with a bar over it)

The sample mean for a sample of size $n$ is approximately $\sim N(\mu,\sigma^2/n)$ where $\mu$ is the population mean and $\sigma^2$ the population variance.