Question

a publisher wants to determine how many copies of a certain book they should print. they have estimated the probability of selling different amounts of the book, and a portion of the probability distribution is given below.

copies	between 20001 and 30000	between 30001 and 40000	between 40001 and 50000	at least 50001

enter your answers for this problem as percentages.
(a) what is the probability that the publisher sells at least 30001 copies of the book?
(b) what is the probability that the publisher sells 30000 copies or fewer of the book?
(c) what is the probability that the publisher sells 20000 copies or fewer of the book?

Explanation:

Step1: Calculate probability of selling at least 30001 copies

We sum the probabilities of selling between 30001 - 40000, 40001 - 50000 and at least 50001 copies. So, $32\%+14\% + 6\%=52\%$.

Step2: Calculate probability of selling 30000 copies or fewer

The total probability is 100%. Probability of selling at least 30001 copies is 52%. So, $100\% - 52\% = 48\%$.

Step3: Calculate probability of selling 20000 copies or fewer

We know probability of selling between 20001 - 30000 is 28%. Probability of selling 30000 copies or fewer is 48%. So, $48\% - 28\%=20\%$.

Answer:

(a) 52%
(b) 48%
(c) 20%