Question

A courier service company has found that their delivery time of parcels are 50 minutes and variance of 25 minutes squared
What is the probability that a randomly selected parcel will take 60 minutes to deliver?

Answer 1

Mean delivery time = 50 minutes

Variance = 25 minutes

probability that a randomly selected parcel will take 60 minutes to deliver

Variance = 25 minutes

Therefore, Standard deviation $= \sqrt{25} =5$

$Z score = \frac{( Given \, value - Mean)}{Standard \,deviation}$

Z score for 60 $=\frac{ (60 - 50)} {5} = 2$

$Z(2) =$ 0.97725