How many months did he read 4 or more books?

What is the standard deviation of the following data set rounded to the nearest tenth? 3, 17, 18, 15, 12, 21, 9

From the top of a tree a bird looks down on a field mouse at an angle of depression of 50°. if the field mouse is 40 meters from the base of the tree, find the vertical distance from the ground to the bird's eyes.

Suppose m: angle a =77 degrees what is the measure of a complement of a complement of angle a, what is a conclusion you can draw about a complement of a complement of an angle