Question: A scale is designed so that when items are weighed, the errors in the indicated weights are normally distributed with a mean 0g and a standard deviation 1g.

(a) If an item is randomly selected and weighed, that is the probability that it has an error between -0.5 g and 0.5g?

(b) If 16 items are randomly selected and weighed, what is the probability that the mean of errors is between -0.5g and 0.5g?

(c) What is the 90 th percentile for the errors?