Suppose the national forest contains 1,000,000 trees, and that the age of trees in this forest is normally distributed with a mean of 225 years, and a standard deviation of 150 years;

-What is the probability that a tree in this forest is more than 135 years old?

-Suppose a sample of 90,000 trees is randomly selected from this forest, calculate the standard deviation of tree age for this sample.

-Calculate the probability that a sample of 40,000 trees drawn at random from this forest has an average age between 223.5 and 226 years old?