Question

The bookstore has 15 new copies and 15 used copies in stock. If 25 people come in one by one to purchase this text, what is the probability that all 25 will get the type of book they want from current stock

Answer 1

Answer:

The probability that all 25 will get the type of book they want from current stock is 0.024

Step-by-step explanation:

21% of all students who have to buy a text for a particular course want a new copy (the successes!), whereas the other 79% want a used copy.

p= 0.21

q=0.79

Let x be the no. of students who want a new copy

x can take values 15,14,13,12,11,10

We are supposed to find probability that all 25 will get the type of book they want from current stock

$P(X=x) =\sum_{x=10}^{15} (0.21)^x (0.79)^{25-x}=0.024$

Hence the probability that all 25 will get the type of book they want from current stock is 0.024