When we use the t-distribution to calculate a confidence interval, we need to assume that the population of interest follows the normal probability distribution.
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Q. 2The farther out into the future that we project the regression trend line, the less reliable the forecasted value will be.
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Q. 3The degrees of freedom are used to determine the critical z-score for the normal distribution when calculating a confidence interval.
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Q. 4The table below shows the number of cars sold last month by seven employees at Concord Motors and their number of years of sales experience.
Experience Sales
1 8
2 6
2 7
4 14
5 9
6 13
8 10
Management would like to use simple regression analysis to estimate monthly car sales using the number of years of sales experience. The sum of squares error for this sample is ________.
A) 13.50
B) 16.00
C) 29.61
D) 37.23
Q. 5AutoTrader.com would like to test if a difference exists in the age of three different types of vehicles currently on the road--trucks, cars, and vans. The following data represent the age of a random sample of trucks, cars, and vans.
Trucks Cars Vans12 8 38 7 79 10 611 7 8Using = 0.05, the conclusion for this hypothesis test would be that because the test statistic is___________________________
___________________________.A
) less than the critical value, we can conclude that there is a difference in the average age of trucks, cars, and vans currently on the road
B) less than the critical value, we cannot conclude that there is a difference in the average age of trucks, cars, and vans currently on the road
C) more than the critical value, we cannot conclude that there is a difference in the average age of trucks, cars, and vans currently on the road
D) more than the critical value, we can conclude that there is a difference in the average age of trucks, cars, and vans currently on the road
Q. 6The degrees of freedom are the number of values that are free to vary given that certain information, such as the sample mean, is known.
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