Suppose the lengths of the pregnancies of a certain animal are approximately normally distributed with mean μ=228 days and standard deviation σ=11 days.

Question

What is the probability that a randomly selected pregnancy lasts less than 224 days?

Answer 1

With mean μ=228 days and standard deviation σ=11 days, what is the probability that a randomly selected pregnancy lasts less than 224 days?

 

!. We need to find the z value, the number of standard deviations from the mean, = (x - μ)/σ =  (224 - 228)/11 = -.3636

 

2. Using a standard normal table, a z score of -.3636 has a p value, probability of, .358 or 35.8%

 

Hope this helps