The Student Room Group
Reply 1
ruth_lou
in a test of 10 true-false questions a student gets 8 correct. the student claims she was not guessing. test at 5% level.

Does this mean X-Bin (10, 1/2)?

if so how do i take the probability of 8, is it....P(x=8)? :smile:

knida
X~Bin(10,p)
H0: p=.5
H1: p>.5 (or 2tailed p no= .5)
then under nul hypthesis see the prabaility is greater than or equal to 8 and if this is less than 5% then u have reason to reject H0
Reply 2
yep, X-Bin (10, 1/2) is correct.

However, you need to find the probability of the student getting 8 or more correct (i.e. P(x>=8)).
You need to do this for all hypothesis tests - I don't really know why.
Reply 3
On second thoughts, I should make this a bit clearer:

If the number she gets right is greater than expected (e.g. 8) you need to find P(X>=8)

If the number she gets right is less than expected (e.g. 3) you need to find P(X<=3)

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