Please help me my homework.

A machine cuts steel to length for nails. The mean length of a nail is 43 millimeters. There is concern that the settings of the machine producing the nails have changed. To test the claim, twelve nails (n = 12) were sampled. The mean of the sample is 41.5 and the standard deviation is 1.784.

a) What is the value of the test statistic?

b) To test the claim at the 0.02 significance level, what is the critical value?

c) To decide if the sample data support the claim that mean length is 43 millimeters, state your decision in terms of the null hypothesis. Use a 0.02 level of significance to test your hypothesis. What is your decision?