Question

The sample mean is 12 for a sample of 26. The sample deviation is 3. Use the .02 level of significance
The following information is available.

H0:  ≤ 10
H1:  > 10

Answer 1

Try a t-test since your sample size is rather small.

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

sample mean = 12
population mean = 10
standard deviation = 3
sample size = 26

Plug in the values and calculate the t-test statistic.

Find the critical value for a one-tailed test at .02 level of significance using 25 for degrees of freedom (df = n - 1). Use a t-table. Compare to your t-test statistic calculated above. If the t-test statistic exceeds the critical value from the table, reject the null. If the t-test statistic does not exceed the critical value from the table, do not reject the null.

I hope this will help.