1.) Recipes for the same type of cookies can vary in terms of ingredients and baking times. From a collection of chocolate chip cookie recipes, a baker randomly selected 5 recipes. From a collection of oatmeal raisin cookie recipes, the baker randomly selected 4 recipes. The mean baking times, in minutes, for each sample were recorded as x¯C and x¯O, respectively. What is the correct unit of measure for the standard deviation of the sampling distribution of x¯C−x¯O?
Minutes

A

Minutes squared

B

Recipes

C

Number of Raisins

D

Number of Chocolate Chips

2.)For a weekly town council meeting in a certain town, the distribution of the duration of the meeting is approximately normal with mean 53 minutes and standard deviation 2.5 minutes. For a weekly arts council meeting in the same town, the distribution of the duration of the meeting is approximately normal with mean 56 minutes and standard deviation 5.1 minutes. Let x¯1 represent the average duration, in minutes, of 10 randomly selected town council meetings, and let x¯2 represent the average duration, in minutes, of 10 randomly selected arts council meetings.

Which of the following is the best reason why the sampling distribution of x¯1−x¯2 can be modeled by a normal distribution?

The sample sizes are equal.

A

Both sample sizes are large enough to satisfy the normality condition.

B

The population distributions are approximately normal.

C

The population standard deviations are assumed equal.

D

The sample sizes are less than 10% of the corresponding population sizes