Question 1203279: A random selection of volunteers at a research institute have been exposed to a typical cold virus. After they started to have cold symptoms, 25 of them were given multivitamin tablets formulated to fight cold symptoms. The remaining volunteers were given placebo tablets. For each individual, the length of time taken to recover from the cold is recorded. At the end of the experiment the following data are obtained.
It is known that the population standard deviation of recovery time from a cold is 1.8 days when treated with multivitamin tablets, and the population standard deviation of recovery time from a cold is 1.5 days when treated with placebo tablets. It is also known that both populations are approximately normally distributed. The researchers claim that the mean recovery time, u1, of the patients treated with multivitamin is not equal to the mean recovery time u2, of the patients who are treated with placebo tablets. At the 0.05 level of significance, is there enough evidence to support this claim? Perform a two-tailed test. Then complete the parts below.
Carry your intermediate computations to at least three decimal places. (If necessary, consult a list of formulas.)
Treated with multivitamin
7.3, 5.2, 2.6, 6.4, 7.3, 6.9, 3, 4.4, 8.2, 5.2
6.9, 2.3, 6.2, 2.6, 7.2, 7.2, 4.6
6.5, 6.7, 4.3, 8, 5.7, 4.5, 1.4, 4.6
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Treated with Placebo
3.5, 5.3, 4.1
2.8, 2.9, 4.7
6.9, 3.9, 5, 4.8
5.5, 3.8
A.State the null hypothesis H0 and the alternative hypothesis
B.Determine the type of test statistic to use (Z, t, Chi-square, or F
C.Find the value of the test statistic to use. Round to 3 or more decimal places.
D.Find two critical values at the 0.05 level of significance. Round to 3 or more decimal places.
E.Can we support the researchers claim that the mean recovery time when treated with multivitamin is not equal to the mean recovery time when treated with placebo? Yes or no
Answer by Theo(13342)   (Show Source):
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