Answer:
7 or 8
Step-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 Â
[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.
