Need help with understanding binomial & geometric probability problems.

Directions: Label each question as geometric or binomial and label the problem as a PDF or as CDF. Give the probability and the x-value along with the number of trials if appropriate. Round to 4 decimal places 1. Athletes. Major universities claim that 72% of the senior athletes graduate that year. Fifty senior athletes attending major universities are randomly selected whether or not they graduate is recorded in the order of selection. a) What is the probability that exactly 40 senior athletes graduated that year? b) What is the probability that fewer than 38 senior athletes graduated that year? c) What is the probability that 40 or more senior athletes graduated that year? d) What is the probability that the first senior athlete to graduate from the selected group was the 5th selected? e) What is the probability that the first senior athlete to graduate from the selected group was within the first 8 selected? f) What is the expected number of senior athletes to graduate that year? g) What is the standard deviation of senior athletes to graduate that year? h) What is the probability that exactly 20 to 25 senior athletes will graduate? i.) Find the mean number of senior athlete graduates before the first one is selected that graduates. 2. Blood. Only 4% people have type AB blood. a) On average, how many donors must be checked to find someone the ist with type AB blood? b) What's the probability that there is a type AB donor among the first 5 people checked? c) What's the probability that first donor found is the 10Th person? d) If 85 donors are checked, how many donors do we expect to have type AB blood? If 85 donors are checked, what is the probability that exactly 3 will have type AB blood? f) What is the probability that at least 3 of the 85 donors will have type AB blood? g) What is the probability that there are no type AB donors in a group of 45 donors? h) What is the probability that there are no more than 2 donors in a group of 45 donors? i) What is the likelihood that there are less than 5 type AB donors in a group of 120? j ) What is the standard deviation for the number of AB donors among a group of 90? k ) 3. Combinations a) An election ballot asks voters to select two city commissioners from a group of six. In how many ways can this be done? b) You are on your way to Hawaii and your parents say you can only take 5 books out of 15 possible books. How many different collections of 5 books can you take