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sarah1004 · Dec 10, 2009, 06:13 PM

State the null and alternative hypotheses.
Some previous studies found that college students averaged 8 hours or so per week on the internet. With more people owning cell phones we think that internet use has decreased maybe because of texting/twittering has increased. We want to test this hypothesis with some sample data from our class survey.
3.0
1.0
2.5
4.0
1.0
2.0
6.0
4.0
2.0
3.0
2.0
2.0
3.0
4.0
2.0
0.2
3.0
4.0
1.0
2.0
1.0
1.5
2.0
1.0
2.0
Please Please help I don't know how to do
State the null and alternative hypotheses this..
Please help me Thanks

galactus · Dec 15, 2009, 07:10 AM

Originally Posted by sarah1004

State the null and alternative hypotheses.
Some previous studies found that college students averaged 8 hours or so per week on the internet. With more people owning cell phones we think that internet use has decreased maybe because of texting/twittering has increased. We want to test this hypothesis with some sample data from our class survey.
3.0
1.0
2.5
4.0
1.0
2.0
6.0
4.0
2.0
3.0
2.0
2.0
3.0
4.0
2.0
0.2
3.0
4.0
1.0
2.0
1.0
1.5
2.0
1.0
2.0
Please Please help I dont know how to do
State the null and alternative hypotheses this..
Please help me Thanks

At what alpha level are you supposed to test?

Let's assume ${\alpha}=.05$ . That is a common one.

The claimed mean is 8. Using your data, the smaple mean is 2.368 and

the sample standard deviation is 1.3127. The sample size is 25.

The claim is that it decreased, so we have a left tailed test.

$H_{0}:{\mu}\geq 8$

$H_{a}:{\mu}<8, \;\ \text{claim}$

$\text{test statistic}=t=\frac{(2.368-8)\sqrt{25}}{1.3127}=-21.45$ .

Because the sample size is less than 30, we use the t-table.

Looking it up, we see the critical value is -1.711.

The test stat is certainly within the rejection region.

With the given data, we REJECT the null hypothesis. We reject even at .0001 because the p value is so low. Since we reject the null hypothesis, then the claim holds water and it is decreasing.