You'd like to analyze some attributes of a typical Mac 'n Cheese pizza from lan's. The percent of the pizza that is covered in macaroni noodles is normally distributed with a (population) standard deviation 0.6. You bought 15 pizzas and calculated the sample average pizza coverage was 61.5. What sample size is necessary to estimate true average pizza coverage if you want the width of a 99% confidence interval to be no greater than 0.20? Round up to the nearest integer.