A pizza delivery shop averages 21 minutes per delivery with a standard deviation of 3 minutes. what is the probability that a pizza takes less than 15 minutes to be delivered?

We have the mean, μ = 21 and the standard deviation, σ = 3

We want P (X<15)

Standardizing gives:

P (X<15) = P (Z< (15-21) / 3)

P (X<15) = P (Z< - 2) ⇒ When the value of the z-score is negative, we will read the value of z<2 on the z-table then subtract the answer from 1

P (X<15) = 1 - P (Z<2)

P (X<15) = 1 - 0.9772

P (X<15) = 0.0228

the probability that pizza takes less than 15 minutes to be delivered is 0.0228 = 2.28%

Round answer as needed