A population is normally distributed with a mean of 40 and a standard deviation of 6. For samples of size 10, what is the probability that the sample mean will be more than 42?

Question

A population is normally distributed with a mean of 40 and a standard deviation of 6.  For samples of size 10, what is the probability that the sample mean will be more than 42?

PsyDAG · Answer

Z = (sample mean - mean)/standard error (SE) of mean

SEm = SD/√(n-1)

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z score.