# 查看完整版本 : 求統計神幫忙,想知道這些題型怎樣做(1)

henryhc20090 2017-8-6 06:47 PM

## 求統計神幫忙,想知道這些題型怎樣做(1)

1.        In order to estimate the difference between the yearly incomes of marketing managers in the East and West of the United States, the following information was gathered.

East                                   West
n1 = 40                      n2 = 45

XBAR1= (in \$1,000)    XBAR2(in \$1,000)

s1 = 6 (in \$1,000)        s2 = 8 (in \$1,000)

(a)Calculate the degrees of freedom of t distribution for this problem.

(b)Develop an interval estimate for the difference between the average yearly incomes of the marketing managers in the East and West. Use  .

(c)At 95% confidence, use the p-value approach and test to determine if the average yearly income of marketing managers in the East is significantly different from the West.
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2.In order to determine whether or not a driver's education course improves the scores on a driving exam, a sample of 6 students were given the exam before and A comparative study of organic and conventionally grown produce was checked for the presence of E. coli.  Results are summarized below.  Is there a significant difference in the proportion of E. Coli in organic vs. conventionally grown produce? Test at  .after taking the course. The results are shown below.

Let d = Score After - Score Before.
Score                              Score
student                Before the Course        After the Course
1                         83                                 87
2                         89                                 88
3                         93                                 92
4                         77                                 75
5                          86                                 93
6                         80                                 85

(a)Compute the test statistic and test to see if taking the course actually increased scores on the driving exam at 95% confidence.

(b)At 95% confidence using the p-value approach, test to see if taking the course actually increased scores on the driving exam.

henryhc20090 2017-8-6 06:48 PM

## 求統計神幫忙,想知道這些題型怎樣做(2

[table][tr][td]1.The grades of a sample of 5 students, selected from a large population, are given below.

72
82
64
92
75
(a)Determine a point estimate for the variance of the population.

(b)Determine a 95% confidence interval for the variance of the population.

(c)At 90% confidence, test to determine if the variance of the population is less than or equal to 64.
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2.Before the presidential debates, it was expected that the percentages of registered voters in favor of various candidates to be as follows.

Percentages[/hr]
Democrats        48%
Republicans        40%
Independent        5%
Undecided        7%
After the presidential debates, a random sample of 2000 voters showed that 1000 favored the Democratic candidate; 780 were in favor of the Republican candidate; 90 were in favor of the Independent candidate, and 130 were undecided. At 95% confidence, test to see if the proportion of voters has changed.
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3.Five hundred randomly selected automobile owners were questioned on the main reason they had purchased their current automobile.  The results are given below.

Styling        Engineering        Fuel Economy        Total
Male                                             70                     110                     160                 340
Female                                            30                       40                       90                 160
100              150                     250                 500

(a)State the null and alternative hypotheses for a contingency table test.

(b)State the decision rule, using a 0.1 level of significance.

(c)Calculate the chi-square test statistic.

(d)Give your conclusion for this test.
[/td][/tr][/table]