The scores on a standardized test have an average of 1200 wi

The scores on a standardized test have an average of 1200 with a standard deviation of 60. A sample of 36 scores is selected. What is the probability that the sample mean will be less than 1210?

Solution

So the probability that the sample mean will be less than 1210 is

P(xbar<1210) = P((xbar-mean)/(s/vn) <(1210-1200)/(60/sqrt(36)))

=P(Z<1)

=0.8413 (from standard normal table)