7. In an orchard, all the trees are either apple or pear trees. There are four times as many apple trees as pear trees. Find the probability that, in a random sample of 10 trees, there are

1. equal numbers of apple and pear trees,
2. more than 7 apple trees. In a sample of 60 trees in the orchard,
3. find the expected number of pear trees.
4. Calculate the standard deviation of the number of pear trees and compare this result with the standard deviation of the number of apple trees.
5. Find the probability that exactly 35 in the sample of 60 trees are pear trees.
6. Find an approximate value for the probability that more than 15 of the 60 trees are pear trees.