Chapter 24, Problem 17E

(a)

To determine

To create an appropriate display of these data and explain what do you see.

Explanation of Solution

In the question, the average numbers of runs scored in American league and National league games are recorded. Thus, the appropriate displays of the following are:

For American league games:

  

For National league:

  

By looking at the bar chart we can say that both the bar graph are uni-modal and approximately symmetric in nature.

(b)

To determine

To estimate the mean number of runs scored in American League games.

Answer to Problem 17E

The mean of runs scored in American league games is $9.854$ .

Explanation of Solution

In the question, the average numbers of runs scored in American league and National league games are recorded. Thus, the mean of runs scored in American league games can be calculated as:

The formulas used in excel to find the mean is as follows:

AVERAGE ( $\text{number1, }\left[\text{number2}\right]$ , ...): Returns the average (arithmetic mean) of the arguments.

American League games
Average	=AVERAGE(C1:C13)

And the result will be as:

American League games
Average	9.854

Thus, the mean of runs scored in American league gamesis $9.854$ .

(c)

To determine

To explain do you think the $10.5$ runs scored per game at Coors in unusual.

Answer to Problem 17E

No, it is not unusual.

Explanation of Solution

In the question, the average numbers of runs scored in American league and National league games are recorded. Now, we think that the $10.5$ runs scored per game at Coors in not unusual because as we look in the graph of the data in part (a), we can say that the $10.5$ runs score is not an outlier. Thus, how can it be unusual then if it is not an outlier.

(d)

To determine

To explain why you should not use two separate confidence interval to decide whether the two leagues differ in average number of runs scored.

Explanation of Solution

In the question, the average numbers of runs scored in American league and National league games are recorded. Now, we should not use two separate confidence interval to decide whether the two leagues differ in average number of runs scored because we want to work directly with the average difference. The two separate confidence intervals does not answer questions about the difference. The difference has a different standard deviation, found by adding variances.