Question

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?

Answer 1

Answer:

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 %)