120g:5kg in simplest form

The first-serve percentage of a tennis player in a match is normally distributed with a standard deviation of 4.3%. if a sample of 15 random matches of the player is taken, the mean first-serve percentage is found to be 26.4%. what is the margin of error of the sample mean? a. 0.086% b. 0.533% c. 1.11% d. 2.22%

If you could answer these your a life saver

In the diagram, ab is tangent to c, ab = 4 inches, and ad = 2 inches. find the radius of the circle.