Question

3. Suppose the time to complete a 200-meter backstroke swim for female competitive swimmers is normally distributed with a mean ? =140 seconds and a standard deviation ?=6 seconds. Suppose that to qualify for the Nationals, a woman must complete the 200-meter backstroke in less than 128 seconds. What proportion of competitive female swimmers will qualify for the Nationals? Give your answer to four decimal places.

Use your calculator. What is the command that you would put in your calculator? What is the proportion you get from the calculator?

Answer 1

3)

Using Ti 84

Access the normalcdf function on the calculator by pressing 2nd .
Then press VARS to access the DISTR menu .
First enter the lower boundary , your lower boundary will be negative infinity .Use a large negative number like -1000 in this cases .
The lower boundary,then press the comma .
Enter the average then press the comma key . Enter the standard deviation and press the end parenthesis key .
Enter to get your answer
normalcdf(-1E99,128,140,6)  

0.0089984

Proportion = 0.0090