Question

Trucks in a delivery fleet travel a mean of 100 miles per day with a standard deviation of 23 miles per day. The mileage per day is distributed normally. Find the probability that a truck drives between 86 and 125 miles in a day. Round your answer to four decimal places.

Answer 1

Answer:

The probability that a truck drives between 86 and 125 miles in a day.

P(86≤ X≤125) = 0.5890 miles

Step-by-step explanation:

Step(i):-

Given mean of the Population = 100 miles per day

Given standard deviation of the Population = 23 miles per day

Let 'X' be the normal distribution

Let x₁ = 86

$Z_{1} = \frac{x_{1} -mean}{S.D} = \frac{86-100}{23} =-0.61$

Let x₂= 86

$Z_{2} = \frac{x_{2} -mean}{S.D} = \frac{125-100}{23} = 1.086$

Step(ii):-

The probability that a truck drives between 86 and 125 miles in a day.

P(86≤ X≤125) = P(-0.61 ≤ Z≤ 1.08)

                      = P(Z≤ 1.08) - P(Z≤ -0.61)

                      = 0.5 +A(1.08) - ( 0.5 - A(-0.61))    

                      = A(1.08) + A(0.61)             ( A(-Z)=  A(Z)

                      = 0.3599 + 0.2291

                     = 0.5890

Conclusion:-

The probability that a truck drives between 86 and 125 miles in a day.

P(86≤ X≤125) = 0.5890  miles per day