statistics
posted by lola .
The mean of math SAT scores is 500 and the standard deviation is 100. A random sample of 64 students from Leeds H.S. received an average of 480. Conduct a hypothesis test to determine if the population mean SAT score for Leeds H.S. is less than 500 with alpha = .05. Determine a pvalue and explain it.
I know I need a onetail test.

Yes, you are correct. This will be a onetailed test (the alternate hypothesis shows a specific direction on a onetailed test). Use a ztest. See your other post for an example on calculating the ztest statistic using a ztest.
Your hypotheses for this problem:
Ho: µ = 500 >null hypothesis
Ha: µ < 500 >alternate hypothesis
The pvalue is the actual level of the test statistic which you can find using a ztable. Compare with .05 to determine whether or not to reject the null. If you reject the null, then you can conclude µ < 500.
I hope this will help get you started.