The mean speed of a sample of vehicles along a stretch of highway is 67 miles per​ hour, with a standard deviation of 3 miles per hour. Estimate the percent of vehicles whose speeds are between 58 miles per hour and 76 miles per hour.​ (Assume the data set has a​ bell-shaped distribution.)

Accepted Solution

Answer:99.85%Step-by-step explanation:Most of today's student calculators have probability distribution functions built in.  Here we are to find the area under the standard normal curve between 58 mph and 76 mph, if the mean speed is 67 mph and the std. dev. is 3 mph.Here's what I'd type into my calculator:normalcdf(58, 76, 67, 3)The result obtained in this manner was 0.9985.  This states that 99.85% of the vehicles clocked were traveling at speeds between 58 mph and 76 mph.