A recent survey by the AAA revealed that 80 of teenage girls

A recent survey by the AAA revealed that 80% of teenage girls text while driving. You have been hired to do a safety presentation to a high school class of 100 teenage girls. You will ask how many of them text while driving.

What is the probability that exactly 75 of these girls text while driving?

What is the probability that at most 75 of these girls text while driving?

What is the probability that at least 75 of these girls text while driving?

Solution

Follow the steps to obtain the required probability.

1. To find exactly 75 of the girls to be texting, do as follows:

Step1. Go to TI83>DISTR>bonompdf( and enter 100,0.80,75.

The output is 0.0439.

2. To find atmost 75 of the girls texting, do as follows:

Step1. Go to TI83>DISTR>binomcdf( and enter 100,0.80,75.

The output is 0.1313.

3. To find at least 75 of these girls texting, do as follows:

Step1. Go to TI83>1-binomcdf and enter 100,0.80, 74.

The output is 0.9125.