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# Hypothesis testing question watch

1. Q: https://imgur.com/a/eni4mIH

Working: https://imgur.com/a/XVLyy1M

Hi, I am not very confident with hypothesis testing. I don't have the solution for this question, so I'd appreciate some correction if I have made a mistake...

Thanks
2. (Original post by coconut64)
Q: https://imgur.com/a/eni4mIH

Working: https://imgur.com/a/XVLyy1M

Hi, I am not very confident with hypothesis testing. I don't have the solution for this question, so I'd appreciate some correction if I have made a mistake...

Thanks
I'll get a statistician to have a look.

Gregorius
3. (Original post by coconut64)
Q: https://imgur.com/a/eni4mIH

Working: https://imgur.com/a/XVLyy1M

Hi, I am not very confident with hypothesis testing. I don't have the solution for this question, so I'd appreciate some correction if I have made a mistake...

Thanks
I presume this is A-level standard?

Much of your working (and conclusion) is correct, but I think you've set up your null hypothesis incorrectly - but I rather think this is due to the poor wording of the question!

I think what they mean you to do is to take the null hypothesis as . You've correctly worked out the z-value of the test statistic - but you need to then think about how to apply this in the context of the null hypothesis.
4. (Original post by Gregorius)
I presume this is A-level standard?

Much of your working (and conclusion) is correct, but I think you've set up your null hypothesis incorrectly - but I rather think this is due to the poor wording of the question!

I think what they mean you to do is to take the null hypothesis as . You've correctly worked out the z-value of the test statistic - but you need to then think about how to apply this in the context of the null hypothesis.

Thanks for the help. I am confused by the question in that case as the question clearly states that you want to prove that mu is greater than £70. Thank you
5. (Original post by coconut64)
Thanks for the help. I am confused by the question in that case as the question clearly states that you want to prove that mu is greater than £70. Thank you
Indeed. But it comes down to asking how the professor proposes to demonstrate that mu is greater than 70. Implicit here is the approach that says "we're going to assume mu equals 70, work out the consequences, and only reject that idea if the consequences are too unusual". In other words, the professor will only consider that he has proved his assertion if the evidence for it is overwhelming.
6. it sounds like a question from an American book. if you are doing UK exams the questions tend to be framed more carefully.
7. (Original post by Gregorius)
Indeed. But it comes down to asking how the professor proposes to demonstrate that mu is greater than 70. Implicit here is the approach that says "we're going to assume mu equals 70, work out the consequences, and only reject that idea if the consequences are too unusual". In other words, the professor will only consider that he has proved his assertion if the evidence for it is overwhelming.

Hi thanks for the explanation. I have tried again and arrived at the same conclusion actually. https://imgur.com/a/xZc3PBK So this doesn't really change the end result ... thanks
8. ???
9. (Original post by coconut64)
Hi thanks for the explanation. I have tried again and arrived at the same conclusion actually. https://imgur.com/a/xZc3PBK So this doesn't really change the end result ... thanks
You're asked to test whether the mean spending is over 70. So this is a one-tailed test and your should be .
10. (Original post by Notnek)
You're asked to test whether the mean spending is over 70. So this is a one-tailed test and your should be .
This is what I did at the beginning and I got the same answer which is that there is a failure to reject H0 at the confidence level of 10%
Working: https://imgur.com/a/XVLyy1M . I don't know if I have solved it right however

Thanks
11. (Original post by coconut64)
This is what I did at the beginning and I got the same answer which is that there is a failure to reject H0 at the confidence level of 10%
Working: https://imgur.com/a/XVLyy1M . I don't know if I have solved it right however

Thanks
I think it’s okay but your null hypothesis should be that mu = 70 as you were told above. Do you know what the correct answer is?
12. (Original post by Notnek)
I think it’s okay but your null hypothesis should be that mu = 70 as you were told above. Do you know what the correct answer is?
No answer is given which is why I'd like some confirmation..... But either way, I get the same answer though. Thanks

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