MULTIPLE CHOICE. Choose the one alternative that best completes the statement or

Question

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. (3 pts each) 1. A survey was conducted to determine the difference in gasoline mileage for two truck models. A random sample was taken for each model of truck, and the mean gasoline mileage, in miles per gallon, was calculated. A 98% confidence interval for the difference in the mean mileage for model A trucks minus the mean milea ge for model B trucks. . . was determined to be (2s, 4 7). a) 98% of model A trucks have a gas mileage that is between 2.5 and 4.7 miles per gallon higher than model B trucks b) The probablty that a randomly selected Model A truck will have a gas mileage that is lower than a randomly selected model B truck is 0.98. Based on this sample, we are 98% confident that the average mileage for model B trucks is between 2.5 and 4.7 miles per gallon higher than the average mileage for model A trucks c) d) The probability that a randomly selected Model A truck will have a gas mileage that is higher than a randomly selected model B truck is 0.98 e) Based on this sample, we are 98% confident that the average mileage for model A trucks is between 2.5 and 4.7 miles per gallon higher than the average mileage for model B trucks. A researcher was interested in comparing the salaries of female and male employees of a particular company. Independent random samples of female employees (sample 1) and male employees (sample 2) were taken to calculate the mean salary, in dollars per week, for each group. A 90% confidence interval for the difference, 1-uz, between the mean weekly salary of all female employees and the mean weekly salary of all male employees was determined to be (-$110, $10). a) 2. 90% of the time females at this company make less than males. b) Based on these data, we are 90% confident that female employees at this company average between S110 less and $10 more per week than the male employees The probability that a randomly selected female employee at this company makes between c) $110 less and $10 more per week than a randomly selected male employee is 0.9. Since O is contained in the interval, the probability that male employees at this company earn the same as females at this company is 0.9. Based on these data, we are 90% confident that male employees at this company average d) e) between $110 less and $10 more per week than the female employees. As the degrees of freedom increase, the mean and standard deviation of the chi-squared distribution a) increase and decrease, respectively b) decrease and increase, respectively. c) are both unaffected. d) increase and increase, respectively. e) decrease and decrease, respectively. The width of the confidence interval for (-) increases as sand sincrease. a) False b) True

Explanation / Answer

The correct option for the first question is e)

In this question we have given the 98% confidence interval for difference of mean of Model A - mean of model B

So from the sample information we are 98% confidence the mean of model A truck are larger than model B truck since lower limit of the interval is greater than 0.

The correct option of second question is d

When 0 is included in the interval then we fail to reject null hypothesis from the available sample.

Mean of chi square distribution = n = degrees of freedom

and variance of chi square distribution = 2*n = 2* degrees of freedom

So when we increase dwgrees of freedom both mean and variance of chi square distribution are increases.

So correct option of third question is d

The given statement is true.

As s1 and s2 increases the pooled standard deviation also increases and so that width of confidence interval also interval.

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.