You invent a new system to make excellent racing tires for the Indianapolis 500/ Your tires are good for an average of 105 miles, with a standard deviation of 7.5 miles. What is the probability that one of your tires can go for at least 44 laps? What is the probability that one of your tires will fail before the end of 36 laps?

Question

You invent a new system to make excellent racing tires for the Indianapolis 500/ Your tires are good for an average of 105 miles, with a standard deviation of 7.5 miles. What is the probability that one of your tires can go for at least 44 laps? What is the probability that one of your tires will fail before the end of 36 laps?

One lap is 2.5 miles.

Answer 1

Convert the laps to miles.

Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to the Z scores.