The average length of an adult blue whate is 30 meters with a standard deviation of 5.7 meters. If a sample of 31 whales is taken, what is the probability that their average lenght differs from the mean by more than 2.0 meters

Answer 1

Use z-scores using sample size:

z = (x - mean)/(sd/√n)

Find two scores:

z = (32 - 30)/(5.7/√31)
z = (28 - 30)/(5.7/√31)

Find the probability between the two z-scores using a z-table. Subtract that value from 1 for your answer.

I hope this will help get you started.