SOLUTION: I was wondering if anyone can tell me if got these right: Suppose that a student needs to buy 6 books for her history course. The number of books that she will be able to find us

Question 313293: I was wondering if anyone can tell me if got these right:
Suppose that a student needs to buy 6 books for her history course. The number of books that she will be able to find used is a binomial random variable X with n = 6 and p = 0.30. In other words, the probability that she will find any given book used is 0.30, and is independent from one book to the next. What is the expected number of used books she will find, E(X)= 1.8
Using Standard Normal Table, what is the probability that Z is less than or equal to 2, P(Z ≤ 2)=0.9772
and finally,
Using Standard Normal Table, find P(-0.1 < Z < 0.5)=.6687
Thanks for all your help,
Donnie
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Suppose that a student needs to buy 6 books for her history course. The number of books that she will be able to find used is a binomial random variable X with n = 6 and p = 0.30. In other words, the probability that she will find any given book used is 0.30, and is independent from one book to the next. What is the expected number of used books she will find, E(X)= np = 1.8
OK
-----------------------------------------
Using Standard Normal Table, what is the probability that Z is less than or equal to 2, P(Z ≤ 2)=0.9772
OK
----------------------
and finally,
Using Standard Normal Table, find P(-0.1 < Z < 0.5)=.6687
No. I get 0.2313
======================
Cheers,
Stan H.
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