The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

Probability question help!

Hi, can anyone talk me through how to answer this question, please?

Would be grateful.

The manager of a University bookstore claims that 50% of its customers are satis ed with
the service and prices.

(a) Assuming that the manager's claim is true, what is the probability that in a random
sample of 200 customers less than 45% are satis ed?
[5]

(b) Suppose that a random sample of 200 of the bookstore's customers has been taken
and 90 of the sampled customers express satisfaction. What does this tell you about
the manager's claim?


Need the answer to A mainly.

Thanks so much!
Anyone, please?
PLEASE?
Original post by slacker07906
PLEASE?


Binomial distribution

p = 0.5
n = 200

Perhaps use Normal approximation
X = satisfied customer

X ~ B(200, 0.5)
Then find P(X < 90). Not sure what to do then? Approximate by normal, maybe, and look it up in a table.
Your question is about hypothesis testing.

a) Yes, you should approximate into a N(100, 50) distribution, treating "less than 45%" to mean "less than 90".
b) Do a hypothesis test according to this: http://stattrek.com/hypothesis-test/proportion.aspx (Significance level is up to you)
(edited 9 years ago)
Original post by Erebusaur
X = satisfied customer

X ~ B(200, 0.5)
Then find P(X < 90). Not sure what to do then? Approximate by normal, maybe, and look it up in a table.


Yeah, I get that.

I just don't know what to do next, which formula to use?

God, I hate statistics :mad:
Original post by shawn_o1
Your question is about hypothesis testing.

a) Yes, you should approximate into a N(100, 50) distribution, treating "less than 45%" to mean "less than 90".
b) Do a hypothesis test according to this: http://stattrek.com/hypothesis-test/proportion.aspx (Significance level is up to you)


Ah, I get it. Thanks so much for this :colondollar:

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you