staticstics
posted by melinda .
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

Use zscores 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 zscores using a ztable. Subtract that value from 1 for your answer.
I hope this will help get you started.