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# Hypothesis testing

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1. A researcher wants to investigate the effects of prenatal alcohol on birth weight. A random sample of n = 16 pregnant rats is obtained. The mother rats are given daily doses of alcohol. At birth, one pup is selected from each litter to produce a sample of n = 16 newborn rats. The average weight for the sample is 15 grams. The researcher wishes to compare the sample with the general population of the rats. It is known that normal newborn rats (not exposed to alcohol) have an average weight of = 18 grams. The weights are normally distributed with = 4. Use 95% confidence with a one-tail test.

2. On an exam given to students at a large number of schools, the mean grade was 74.5 and the standard deviation was 8.0. At one particular school where 225 students took the exam, the mean grade was 75.9. Discuss the significance of this result from the viewpoint of (a) a one-tailed test, (b) two-tailed test. Test at alpha equal .01 and at .05.

https://brainmass.com/statistics/hypothesis-testing/investigate-effects-prenatal-alcohol-birth-weight-156390

#### Solution Preview

Calculations are done in Excel.

Statistics analysis
1. A researcher wants to investigate the effects of prenatal alcohol on birth weight. A random sample of n = 16 pregnant rats is obtained. The mother rats are given daily doses of alcohol. At birth, one pup is selected from each litter to produce a sample of n = 16 newborn rats. The average weight for the sample is 15 grams. The researcher wishes to compare the sample with the general population of the rats. It is known that normal newborn rats (not exposed to alcohol) have an average weight of = 18 grams. The weights are normally distributed with = 4. Use 95% confidence with a one-tail test.
The null hypothesis tested is
H0: The population mean weight newborn rats(Exposed to alcohol) =18 grams
Vs
H1: The population mean weight newborn rats(Exposed to alcohol) <18 grams
The test statistic used is
Rejection Criteria: Reject the null hypothesis, if the calculated value of ...

#### Solution Summary

Step by step method for testing the hypothesis under 5 step approach is discussed here. Excel template for each problem is also included. This template can be used to obtain the answers of similar problems.

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