We would like to estimate the true mean yield of milk for all cows of a certain breed. It is required that our estimate be accurate to within 5,41 litres of the true mean, A sample of 15 cows is available, and it is known that milk yields follow a normal . distribution with standard deviation 10.2 litres. The maximum confidence level that can be attained for a confidence interval which meets our requirements is approximately: 99 95 90 80 JPG