Question

The time required to finish a test is normally distributed with a mean of 60 minutes and a standard deviation of 10 minutes. What is the probability that a student will finish the test in less than 70 minutes?

Answer 1

The answer is 0.3413 because Explanation:

z=x−uσ, where u=6 0andσ=10.

Therefore the probability student finish the test between 50 to 60 minutes is,

P(50≤x≤60)=P(50−6010≤z≤60−6010)

P(−1≤z≤0)=P(z≤0)−P(z≤−1)

=0.5000−0.1587=0.3413