What have you done with this problem? What is the null hypthesis and the alternative one? Do you know how to start the problem? How to get z here? Is it a two tailed test or a one tailed? Can I see a little of your work?
A standard measure of test anxiety is knnown to produce a u=19. In the sample you draw of 86 the mean is equal 17.5 with a standard deviation s=10.
a-Use a level of 0.05 to test the hypothesis that the mean is less than 19. b-find the 95% one sample confidence interval for the mean.