Stat Homework for courseworkhero.co.uk

For each hypothesis test show all four steps. Number 5 just respond to each item.

1. At a local college, 65 female students were randomly selected and it was found that their mean monthly income was $623 with a standard deviation of $121.50. Also 75 male students were randomly selected and their mean monthly income was $665 with a standard deviation of $168.70. Test the claim that the males have a higher monthly income than the females. Use alpha= .01.

2. A study was conducted to determine if the salaries of elementary school teachers from two neighboring districts were equal. A sample of 15 teachers from each district was randomly selected. “The mean from the first district was” $28,900 with a standard deviation of $2300. The mean from the second district was $30,300 with a standard deviation of $2100. Use alpha=.05.

3. A pharmaceutical company wishes to test a new drug with the expectation of lowering cholesterol levels. Ten subjects are randomly selected and pretested. The results are listed below. The subjects were placed on the drug for a period of 6 months, after which their cholesterol levels were tested again. The results are listed below. (All units are milligrams per deciliter.) Test the company’s claim that the drug lowers cholesterol levels using alpha =.01.

Subject 1 2 3 4 5 6 7 8 9 10
Before 195 225 202 195 175 250 235 268 190 240

After 180 220 210 175 170 250 205 250 190 225

4. A recent survey showed that in a sample of 100 elementary school teachers,15 smoked. In a sample of 180 high school teachers, 36 smoked. Is the proportion of high school teachers who smoke greater than the proportion of elementary teachers who smoke? Use alpha=.01.

5. The data below are the final exam scores of 10 randomly selected statistics students and the number of hours they studied for the exam. Find the equation of the regression line for the given data.

Hours,x 3 5 2 8 2 4 4 5 6 3 Scores,y 65 80 60 88 66 78 85 90 90 71 a) Does a scatter plot indicate a correlation? If so, is it positive or negative?

b) Find r, check for its significance at alpha =.05; use table 11.

c) Draw the regression line through the scatter plot and count the number of points it intersects.

d) Explain r squared.

e) Given : x1=7hrs., x2=4.5hrs. Find : y1= , y2= .

6. A random sample of 160 car crashes are selected and categorized by age. The results are as follows : 20% for the under 26 group, 39% for the 26-45 group,29% for the 46-65 group, and 12% for the group over 65. Does this sample fit a uniform distribution? Use alpha =.05.(There are four groups, if they all had the same rate it would be 25% in each group.

7. The contingency table below shows the results of a random sample 200 state representatives that was conducted to see whether their opinions on a bill are related to their party affiliation. Is party affiliation and opinion independent? Use alpha =.01.

Opinion

Party Approve Disapprove No Opinion Republican 42 20 14 Democrat 50 10 18 Independent 16 21 9