Edexcel S2 Exam Paper January 2011 14/01/11

Question 2 seems to be causing a lot of hassle especially for the conclusion part.

I put:

H0: p=0.2
H1: p>0.2

and you reject H0 if P(X>(or equal to)4) <(or equal to) 0.05

which gives you 1 - P(X<(or equal to)3) <(or equal to) 0.05

end result was something like 0.12... <(or equal to) 0.05 which is not true, so there is insufficient evidence to reject H0, meaning we cannot conclude whether the teacher's claim was right or wrong.

Did anyone else put that?

Your testing to see if the teachers claim is right or wrong, if you accept H0 then what he claims is right, if you reject H0 and accept H1 you are rejecting what he said.

I know So was it just 1 mark u lost? Who knows it might still be 100UMS

Ah I see... but does that mean I lost a mark for not giving a correct conclusion in contexts?

.... just would like some explanation

Most of people here seems to be confused with the wording of that question 2.
I am confident that this is true:
It was 10 questions, so n=10 and 5 answers to each question, p=0.2. Therefore, X--B(10,0.2)
The student achieved 4 correct answers and this is 40% of the paper, but in theory it should be 20% (100*0.2). So he infact got MORE than normal. So the teacher said he was guessing, so we are testing whether or not p >0.2 because the student got 40% which is > than 20%.
.....X--B(10,0.2).....
H1: p = 0.2
Ho: p = >0.2
5% Significance level
Because we are testing its > than 20%, it is:
P(X>=4) = 1 - P(X<=3)....which came to around 0.12....this is >0.05(5%), so Reject H1, not significant and therefore there is sufficient evidence that the probability of of correctly answering is still 0.2. So the teacher's claim is CORRECT in saying that he was guessing.

I hope this can clear the confusion

Most of people here seems to be confused with the wording of that question 2.
I am confident that this is true:
It was 10 questions, so n=10 and 5 answers to each question, p=0.2. Therefore, X--B(10,0.2)
The student achieved 4 correct answers and this is 40% of the paper, but in theory it should be 20% (100*0.2). So he infact got MORE than normal. So the teacher said he was guessing, so we are testing whether or not p >0.2 because the student got 40% which is > than 20%.
.....X--B(10,0.2).....
H1: p = 0.2
Ho: p = >0.2
5% Significance level
Because we are testing its > than 20%, it is:
P(X>=4) = 1 - P(X<=3)....which came to around 0.12....this is >0.05(5%), so Reject H1, not significant and therefore there is sufficient evidence that the probability of of correctly answering is still 0.2. So the teacher's claim is CORRECT in saying that he was guessing.

I hope this can clear the confusion

Most of people here seems to be confused with the wording of that question 2.
I am confident that this is true:
It was 10 questions, so n=10 and 5 answers to each question, p=0.2. Therefore, X--B(10,0.2)
The student achieved 4 correct answers and this is 40% of the paper, but in theory it should be 20% (100*0.2). So he infact got MORE than normal. So the teacher said he was guessing, so we are testing whether or not p >0.2 because the student got 40% which is > than 20%.
.....X--B(10,0.2).....
H1: p = 0.2
Ho: p = >0.2
5% Significance level
Because we are testing its > than 20%, it is:
P(X>=4) = 1 - P(X<=3)....which came to around 0.12....this is >0.05(5%), so Reject H1, not significant and therefore there is sufficient evidence that the probability of of correctly answering is still 0.2. So the teacher's claim is CORRECT in saying that he was guessing.

I hope this can clear the confusion

Most of people here seems to be confused with the wording of that question 2.
I am confident that this is true:
It was 10 questions, so n=10 and 5 answers to each question, p=0.2. Therefore, X--B(10,0.2)
The student achieved 4 correct answers and this is 40% of the paper, but in theory it should be 20% (100*0.2). So he infact got MORE than normal. So the teacher said he was guessing, so we are testing whether or not p >0.2 because the student got 40% which is > than 20%.
.....X--B(10,0.2).....
H1: p = 0.2
Ho: p = >0.2
5% Significance level
Because we are testing its > than 20%, it is:
P(X>=4) = 1 - P(X<=3)....which came to around 0.12....this is >0.05(5%), so Reject H1, not significant and therefore there is sufficient evidence that the probability of of correctly answering is still 0.2. So the teacher's claim is CORRECT in saying that he was guessing.

I hope this can clear the confusion

Actually you should probably put &quot;there is insufficient evidence that the teacher's claim was incorrect&quot;
They still may have been guessing but this hypothesis test can not prove it at the 5% confidence interval.