91Ó°ÊÓ

A \(\$1\) scratch off lotto ticket will be a winner one out of five times. Out of a shipment of \(n=190\) lotto tickets, find the probability for the lotto tickets that there are

a. somewhere between \(34\) and \(54\) prizes.

b. somewhere between \(54\) and \(64\) prizes.

c. more than \(64\) prizes.

Facebook provides a variety of statistics on its Web site that detail the growth and popularity of the site.

On average, 28 percent of 18 to 34 year olds check their Facebook profiles before getting out of bed in the morning. Suppose this percentage follows a normal distribution with a standard deviation of five percent.

a. Find the probability that the percent of 18 to 34-year-olds who check Facebook before getting out of bed in the morning is at least 30 .

b. Find the ${95}^{\text{th}}$ percentile, and express it in a sentence.

What does standardizing a normal distribution do to the mean?