Sir, I am stuck on this question

(b) A company produces copper wire to a particular specification of breaking strength using four different types of machines (A, B, C and D). One machine of each type is selected at random and five copper wire samples are measured from each machine. The measurements were: Machine type A B C D Sample wire 1 15.2 13.7 15.0 14.8 Sample wire 2 16.4 13.9 14.9 13.8 Sample wire 3 15.5 14.0 14.7 12.9 Sample wire 4 15.9 12.9 15.2 13.5 Sample wire 5 16.1 13.0 14.5 14.0 Sample mean 15.82 13.50 14.86 13.80 You are given that: 5 EX - na? = 21.0095 where the overall sample mean is a = 14.495. i. Test the null hypothesis that the mean breaking strengths of the four types of machines are the same. Use a 1% significance level. (6 marks) ii. Compute a 95% confidence interval for the difference of the mean breaking strengths between machine types A and B