Question

Harlee uses a device to convert her electronic textbook into braille. Unfortunately, the textbook did not include text descriptions of the diagrams, and 2/3 of the pages have diagrams. Let N be the number of pages Harlee reads to reach the first page with a diagram. Assume that the probability of each page having a diagram is independent. Find the mean and standard deviation of N. Round your answers to one decimal place.

Answer 1

Mean: 1.5

Standard Deviation: 0.9

Explanation:

2/3 of the pages have diagrams, and N is the number of pages Harlee reads to reach a page with a diagram. In order to find the mean, divide 1/(2/3) to get 1.5 as your mean, and then divide sqrt(1-(2/3))/2/3 to get .8660, which rounds to .9.