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The distribution of grade point averages (GPAs) for a certain college is approximately Normal with a mean of 2.5 and a standard deviation of 0.6. The minimum possible GPA is 0.0 and the maximum possible GPA is 4.33. Any student with a GPA less than 1.0 is put on probation, while any student with a GPA of 3.5 or higher is on the dean’s list. About what percent of students at the college are on probation or on the dean’s list?

a.0.6b.4.7c.5.4d.94.6e.95.3

Short Answer

Expert verified

The correct option is:

c.5.4percent of students at the college are on probation or on the dean’s list

Step by step solution

01

 Step 1: Given information 

We have to tell percent of students at the college are on probation or on the dean’s list.

02

Explanation 

The college are on probabtion:

P(X1.0orX3.5)=P(Z<-2.50orZ>1.67)

=P(Z<-2.50)+1-P(Z<1.67)

=0.0062+1-0.9525

=5.4%

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Most popular questions from this chapter

Mrs. Woods and Mrs. Bryan are avid vegetable gardeners. They use different fertilizers, and each claims that hers is the best fertilizer to use when growing tomatoes. Both agree to do a study using the weight of their tomatoes as the response variable. Each planted the same varieties of tomatoes on the same day and fertilized the plants on the same schedule throughout the growing season. At harvest time, each randomly selects 15 tomatoes from her garden and weighs them. After performing a two-sample t test on the difference in mean weights of tomatoes, they gett=5.24 andP=0.0008. Can the gardener with the larger mean claim that her fertilizer caused her tomatoes to be heavier?

a. Yes, because a different fertilizer was used on each garden.

b. Yes, because random samples were taken from each garden.

c. Yes, because the P-value is so small.

d. No, because the condition of the soil in the two gardens is a potential confounding variable.

e. No, because15<30

Treating AIDS The drug AZT was the first drug that seemed effective in delaying

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Researchers suspect that Variety A tomato plants have a different average yield than Variety B tomato plants. To find out, researchers randomly select10Variety A and10Variety B tomato plants. Then the researchers divide in half each of10small plots of land in different locations. For each plot, a coin toss determines which half of the plot gets a Variety A plant; a Variety B plant goes in the other half. After harvest, they compare the yield in pounds for the plants at each location. The10differences (Variety A − Variety B) in yield are recorded. A graph of the differences looks roughly symmetric and single-peaked with no outliers. The mean difference is x-A-B=0.343051526=0.200=20%x-A-B=0.34and the standard deviation of the differences is s A-B=0.833051526=0.200=20%=sA-B=0.83.Let μA-B=3051526=0.200=20%μA−B = the true mean difference (Variety A − Variety B) in yield for tomato plants of these two varieties.

A 95% confidence interval forμA-B3051526=0.200=20%μA-Bis given by

a. 0.34±1.96(0.83)3051526=0.200=20%0.34±1.96(0.83)

b.0.34±1.96(0.8310)3051526=0.200=20%0.34±1.96(0.8310)

c. 0.34±1.812(0.8310)3051526=0.200=20%0.34±1.812(0.8310)

d. 0.34±2.262(0.83)3051526=0.200=20%0.34±2.262(0.83)

e.0.34±2.262(0.8310)3051526=0.200=20%0.34±2.262(0.8310)

You can find some interesting polls online. Anyone can become part of the sample just by clicking on a response. One such poll asked, “Do you prefer watching first-run movies at a movie theater, or waiting until they are available to watch at home or on a digital device?” In all, 8896people responded, with only 12%(1118people) saying they preferred theaters. You can conclude that

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b. the high nonresponse rate prevents us from drawing a conclusion.

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d. the poll uses voluntary response, so the results tell us little about all American adults.

e. American adults strongly prefer seeing movies at a movie theater.

At a baseball game, 42of 65randomly selected people own an iPod. At a rock concert occurring at the same time across town, 34of 52randomly selected people own an iPod. A researcher wants to test the claim that the proportion of iPod owners at the two venues is different. A 90%confidence interval for the difference (Game − Concert) in population proportions is (0.154,0.138). Which of the following gives the correct outcome of the researcher’s test of the claim?

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