A recent article in a computer magazine suggested that the mean time to fully learn a new software program is 40 hours. A sample of 100 first-time users of a new statistics program revealed the mean time to learn it was 39 hours with the standard deviation of 8 hours. At the 0.05 significance level, can we conclude that users learn the package in less than a mean of 40 hours?

Answer 1

Ho: µ = 40 -->population mean = 40
Ha: µ < 40 -->population mean < 40

Using a one-sample z-test:

z = (sample mean - population mean)/(standard deviation divided by the square root of the sample size)

With your data:
z = (39 - 40)/(8/√100)

Finish the calculation. Determine whether or not to reject the null using 0.05 level of significance for a one-tailed test.

I hope this will help.