A normal distribution is observed from the times to complete an obstacle course. The mean is 69 seconds and the standard deviation is 6 seconds. Using the Empirical Rule, what is the probability that a randomly selected finishing time is greater than 87 seconds?

P (z > 87) < 0,0015

P (z > 87) < 0,15 %

Step-by-step explanation:

Applying the simple rule that:

μ ± 3σ, means that between

μ - 9 = 60 and

μ + 9 = 78

We will find 99,7 of the values

And given that z (s) = 87 > 78 (the upper limit of the above mention interval) we must conclude that the probability of find a value greater than 87 is smaller than 0.0015 (0r 0,15 %)