You are looking for a t-test for the difference in means. One tailed test.

Let be the population mean of the sample and

let be the population mean of the sample

Your hypothesis will be:

Give this article a read (problem 2 in particular) to help find the test statistic, degrees of freedom and critical value.

Hint: In your case the difference in means is zero.

Reject if

I suggest you test your hypothesis at