Will someone please tell me how to find the interest? Example problem is attached!

Abicycle training wheel has a radius of 3 inches. the bicycle wheel has a radius of 10 inches.approximately how much smaller, in square inches and rounded to the nearest hundredth, is the area of the training wheel than the area of the regular wheel? *

If p(a) = 0.70 and p(b) = 0.20, then a and b are independent events if

How can you find the mean absolute deviation (mad) for this set of data?