(a) is already done. (b) needs to be completed.

Suppose the sediment density (g/cm) of a randomly selected specimen from a certain region is normally distributed with mean2.63and standard deviation0.70.(a) If a random sample of 25 specimens is selected, what is the probability that the sample average sediment density is at most 3.00? Between2.63and 3.00? (Round your answers to four decimal places.)

at most 3.00	0.9959
between2.63and 3.00	0.4959

(b) How large a sample size would be required to ensure that the first probability in part (a) is at least 0.99? (Round your answer up to the nearest whole number.)