3 mcqs – the regression analysis

1. The regression analysis below relates average annual per capita beef consumption (in pounds) and the independent variable “average annual beef price” (in dollars per pound).

The coefficient on beef price tells us that:

A. For every price increase of $1, average beef consumption decreases by 9.31 pounds.
B. For every price increase of $1, average beef consumption increases by 9.31 pounds.
C. For every price increase $9.31, average beef consumption decreases by 1 pound.
D. For price increase of $9.31, average beef consumption increases by 1 pound.

2. Two semiconductor factories are being compared to see if there is a difference in the average defect rates of the chips they produce. In the first factory, 250 chips are sampled. In the second factory, 350 chips are sampled. The proportions of defective chips are 4.0% and 6.0%, respectively. 

Using a confidence level of 95%, which of the following statements is supported by the data?

A. There is not sufficient evidence to show a significant difference in the average defect rates of the two factories.
B. There is a significant difference in the average defect rates of the two factories.
C. The first factory’s average defect rate is lower than the second factory’s on 95 out of 100 days of operation.
D. None of the above 

3. Preliminary estimates suggest that about 58% of students at a state university favor implementing an honor code. 

To obtain a 95% confidence interval for the proportion of all students at the university favoring the honor code, what is the minimum sample size needed if the total width of the confidence interval must be less than 5 percentage points (i.e., the confidence interval should extend at most 2.5 percentage points above and below the sample proportion)?

A. 375
B. 264
C. 1,498
D. The answer cannot be determined from the information given.