Two spheres have diameters of 20 units and 40 units. What is the ratio of their surface areas, in simplest form?

Which function has an inverse function? a. f(x)= |x+3|/5 b. f(x)= x^5-3 c. f(x)= x^4/7+27 d. f(x)= 1/x²

There are three bags: a (contains 2 white and 4 red balls), b (8 white, 4 red) and c (1 white 3 red). you select one ball at random from each bag, observe that exactly two are white, but forget which ball came from which bag. what is the probability that you selected a white ball from bag a?

Assume that y varies inversely with x. if y=1.6 when x=0.5 find x when y=3.2