# Thread: Stats: Correct or not?

1. ## Stats: Correct or not?

Can someone check my work?

Q
1. A recent study found that, at most, 32% of people who have been in a plane crash have died. In a sample of 100 people who were in a plane crash, 38 died. Is the study statement believable?

Solution:

H(null): P= 0.32
H(alternative): P>0.32 Right tailed

P(hat): 0.38
P= 0.32
n= 100

Then you use the test statistic

z= P(hat)-P/Sqrt(pq/n)
z= 0.38-0.32/sqrt(0.32 x 0.68/100)~ 1.29

So I look for the area on the z score chart and it should be 0.90147. However since that's the area on the left side of the z score. So i must do 1-0.90147= .0985

.0985<0.05 so Reject H(null).....So the statement is believable right?

2. What alpha level are you using?. You didn't say. I assumed .05

$\displaystyle H_{0}\leq{0.32}$(claim)
$\displaystyle H_{a}>0.32$

Test stat = 1.2862

critical value = 1.6449

p value = 0.0992

Do not reject the null hypothesis.

There is not enough evidence at the 5% level to reject the claim that at most 32% of plane crash victims die.

The claim is valid.

If you test at alpha = 0.1, then you can reject.

3. Originally Posted by Nimmy
Can someone check my work?

Q
1. A recent study found that, at most, 32% of people who have been in a plane crash have died. In a sample of 100 people who were in a plane crash, 38 died. Is the study statement believable?

Solution:

H(null): P= 0.32
H(alternative): P>0.32 Right tailed

P(hat): 0.38
P= 0.32
n= 100

Then you use the test statistic

z= P(hat)-P/Sqrt(pq/n)
z= 0.38-0.32/sqrt(0.32 x 0.68/100)~ 1.29

So I look for the area on the z score chart and it should be 0.90147. However since that's the area on the left side of the z score. So i must do 1-0.90147= .0985

.0985<0.05 so Reject H(null).....So the statement is believable right?
Assuming your arithmetic is right wha you have is:

0.0985>0.05 so we do not reject H(null) at the .....So the statement is believable in that we do not reject the hypothesis at this level.

RonL

RonL

4. Originally Posted by galactus
What alpha level are you using?. You didn't say. I assumed .05

$\displaystyle H_{0}\leq{0.32}$(claim)
$\displaystyle H_{a}>0.32$

Test stat = 1.2862

critical value = 1.6449

p value = 0.0992

Do not reject the null hypothesis.

There is not enough evidence at the 5% level to reject the claim that at most 32% of plane crash victims die.

The claim is valid.

If you test at alpha = 0.1, then you can reject.
Is that another way you can solve it? Is my work wrong? How did you get the critical value?

5. Originally Posted by CaptainBlack
Assuming your arithmetic is right wha you have is:

0.0985>0.05 so we do not reject H(null) at the .....So the statement is believable in that we do not reject the hypothesis at this level.

RonL

RonL
oh lol you right. I assume it was 0.5 instead of 0.05