Question

Trucks in a delivery fleet travel a mean of 110 miles per day with a standard deviation of 18 miles per day. The mileage per day is distributed normally. Find the probability that a truck drives between 138 and 149mmiles in a day. Round your answer to four decimal places.

Answer 1

Solution :

Given that ,

mean = = 110

standard deviation = = 18

P(138 < x < 149) = P((138 - 110)/ 18) < (x - ) /  < (149 - 110) / 18) )

= P(1.56 < z < 2.17)

= P(z < 2.17) - P(z < 1.56)

= 0.9850 - 0.9406 Using standard normal table,  

Probability = 0.0444

The probability that a truck drives between 138 and 149 mmiles in a day is 0.0444.