مساعدة في احصاء اعمال 271

[man89]

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a hypothesis will test that two population means are equal. a sample of 10 with a standard deviation of 3 is selected from the first population and a smaple of 3 is selected from the first population. the standard deviations are not equal. testing the claim at the .01 level, what is the critical value? Assume unequal standard deviations
a. 2.845
b. 2.787
c. 2.807
d. 2.977







2.Suppose that an automobile manufacturer designed a radically new lightweight engine and wants to recommend the grade of gasoline that will have the best fuel economy. The four grades are: regular, below regular, premium, and super premium. The test car made three trial runs on the test track using each of the four grades and the miles per gallon recorded. At the 0.05 level, what is the critical value of F used to test the hypothesis that the miles per gallon for each fuel is the same.

Kilometers per liter
Regular Below Regular Premium Super Premium
39.31 36.69 38.99 40.04
39.87 40.00 40.02 39.89
39.87 41.01 39.99 39.93

A) 1.96
B) 4.07
C) 2.33
D) 12.00




A random sample of 30 executives from companies with assets over $1 million was selected and asked for their annual income and level of education. The ANOVA comparing the average income among three levels of education rejected the null hypothesis. The Mean Square Error (MSE) was 243.7. The following table summarized the results:


1. When comparing the mean salaries to test for differences between treatment means, the t statistic is based on:
A) The treatment degrees of freedom.
B) The total degrees of freedom.
C) The error degrees of freedom
D) The ratio of treatment and error degrees of freedom








Several employees have submitted different methods of assembling a subassembly. Sample data for each method are:

Minutes Required for Assembly
Sample Lind’s Szabo’s Carl’s Manley’s
Number Method Method Method Method
1 16.6 22.4 31.4 18.4
2 17.0 21.5 33.4 19.6
3 16.9 22.6 30.1 17.6



how many treatments are there?
a-3
b-4
c-12
d-0

[man89]

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