Question

SOMEONE PLEASE HELP

Drivers on the highway drive at a mean speed of 65 miles per hour, with a standard deviation of 10
miles per hour. If you want to know the probability a randomly selected car will drive at a speed between 55 and 70 miles per hour, what would you enter on the calculator?

Answer 1

See below

Explanation:

On a TI-84, select 2nd+DISTR, then select normalcdf. This is the normal cummulative distributive function which determines the percentage of data that falls between a lower and higher parameter given the mean and standard deviation in a normal distribution.

Next, you would put 55 for lower, 70 for higher, the mean (μ) as 65, and the standard deviation σ as 10. After pressing ENTER, you will get the result of 0.5328072082

This means that 53.28% of the data fall between 55 and 70 mph given a mean of 65 and a standard deviation of 10.