17) Hardboard is graded with the following frequencies: Grade A: 1/5 Grade B: 3/4 Cull: 1/20 If six pieces come off of a hot press, find the probability that two are Grade A, three are Grade B, and one is a Cull. 18) For an environmental group, it is known that 75% of their door-to-door solicitations result in a donation of some kind. Find the probability that of the next 5 visits ... a) ... at least 3 will be refusals. b) ...3 of the next 5 visits will result in donations. c) ...the first refusal will occur on the fifth visit. d) ...the second refusal will occur on the fifth visit. e) ...the third donation will be made on the fifth visit