An experimenter fed different rations, A and B, to two groups of 100 chicks each. Assume that all factors other than rations are the same for both groups. Of the chicks fed ration A, 12 died, and of the chicks fed ration B, 7 died. (a) (5pts) Construct a 99% confidence interval for the true difference in mortality rates for the two rations. (b) (3 pts) Can you conclude that there is a difference in the mortality rates for the two rations