Question

If an hourglass takes an average of 1 hour to empty a full cycle, what probability of time does it take longer than 72 minutes if the standard deviation is 5 minutes? (Make sure to use a percentage!)

Answer 1

Answer:

0.82%

Step-by-step explanation:

First find the z-score.

z = (x − μ) / σ

z = (72 − 60) / 5

z = 2.4

Use a chart or calculator to find the probability.

P(Z > 2.4) = 1 − P(Z < 2.4)

P(Z > 2.4) = 1 − 0.9918

P(Z > 2.4) = 0.0082