Suppose that 25% of all students who have to buy a physical copy of the 9th Edition of our textbook want a new copy (the "successes"), whereas the other 75% want a used copy. Each chooses independently of the others. Consider randomly selecting 30 purchasers. a) What is the expected value of the number of students who want a new copy of the book? Please write out all formulas in your work. Answer:

Answer:7 or 8Step-by-step explanation:This situation can be modeled with the Binomial Distribution which give the probability of an event that occurs exactly k times out of n, and is given by [tex]\large P(k;n)=\binom{n}{k}p^kq^{n-k}[/tex] where  [tex]\large \binom{n}{k}[/tex]= combination of n elements taken k at a time. p = probability that the event (“success”) occurs once q = 1-p In this case, the event “success” is wanting a new copy  of the book with probability 25% = 0.25 and n=30 students randomly chosen. The expected value for a binomial distribution is the mean np, so in this case the expected value of the number of students who want a new copy of the book would be np = 30*0.25 = 7.5 To make sense of this value, we could say that 7 or 8 students out of 30 want a new copy of the book.