Suppose you have a random sample of 50 of these animals. What is the probability that the mean life span of the sample group is between 15 and 20 years?

In what I know of this problem and what you told me I think there is a 1/2 chance!

think about it, if the life span is 15 years old with standard deviation of 3 then that means we can have bats from 12~18 years old and the mean of the 50 numbers can be anything between that depending on the results we got. Then half of values in interval 12~18 is over 15 which gives it a 1/2 probability!

r and t.

both are 64 degrees.