A manufacturer knows that their items have a normally distributed length with a mean of 5.5 inches and standard deviation of 1.1 inches.

Question

A manufacturer knows that their items have a normally distributed length with a mean of 5.5 inches and standard deviation of 1.1 inches. If 15 items are chosen at random what is the probability that their mean length is less than 5.3 inches?

Answer 1

Open Desmos Graphing Calculator. Select the calculator keyboard. Select functions, and under distributions, select Normaldist. In the parenthesis, enter the mean, 5.5, and the std, dev. 1.1. Check the 'Find CDF' box, and enter 5.3 in the Max area. Leave the Min are at -∞, and press enter. The probability is 0.4278