Question

1. The data below give the weights in ounces of randomly-selected bars of bath soap produced by two different molding machines.

	Weights (ounces)
Machine 1	11.4 12.4 12.1 11.8 11.8 11.7 12.3 12.0 11.8
Machine 2	13.0 12.4 12.4 12.1 12.3 12.1 12.5 12.0 12.1

The question of interest is whether these two molding machines produce soap bars of differing average weight. The computed test statistic was found to be -2.75. Find the approximate P-value for the this test assuming that the weights for the two machines are approximately normal with 16 degrees of freedom.

a.

between 0.05 and 0.10

b.

between 0.01 and 0.02

c.

between 0.02 and 0.05

d.

between 0.005 and 0.01

2. A study is conducted to determine whether the proportion of airline passengers complaining with post-flight respiratory symptoms is larger for flights that do not circulate cabin air than for flights that do circulate the air. After checking to make sure that all of the necessary conditions were met, we calculated the value of the z test statistic to be z = 0.84. Which of the following is the P-value associated with this test?

A.0.7995

b.0.2005

c.0.599

d.0.401

e.0

3. The data below give the weights in ounces of randomly-selected bars of bath soap produced by two different molding machines.

	Weights (ounces)
Machine 1	11.4 12.4 12.1 11.8 11.8 11.7 12.3 12.0 11.8
Machine 2	13.0 12.4 12.4 12.1 12.3 12.1 12.5 12.0 12.1

The question of interest is whether these two molding machines produce soap bars of differing average weight. The computed test statistic was found to be -2.75. Draw your conclusion using a 5% level of significance. Assuming weights are normally distributed with 16 degrees of freedom.

	a.	Machine 1 produces soap bars lighter than those that machine 2 produces.
	b.	The two molding machines produce soap bars of differing weight.
	c.	There is not enough evidence that the two molding machines produce soap bars of differing weight.
	d.	Machine 1 produces soap bars heavier than those that machine 2 produces.

4. Stress levels were measured on a scale of 0 – 5 for a sample of 5 UTSA students with a rating of 5 being the highest stress level. Stress level was measured before final exams were taken, and then again before students received their final grade in the course. At a 0.01 level of significance, test if stress levels are different for students before the final exam is taken and before they receive their course grade. Calculate the test statistic.

Before Final Exam	5	4	5	5	3
After Final Exam (Before Receiving Grade)	3	5	4	5	1

	a	-0.8
	b	-3.6
	c	-4.6
	d	-1.38

5. The data below give the weights in ounces of randomly-selected bars of bath soap produced by two different molding machines.

	Weights (ounces)
Machine 1	11.4 12.4 12.1 11.8 11.8 11.7 12.3 12.0 11.8
Machine 2	13.0 12.4 12.4 12.1 12.3 12.1 12.5 12.0 12.1

The question of interest is whether these machine1 produces lighter soap bars than that of machine 2. The computed test statistic was found to be -2.75. Find the approximate P-value for the this test assuming that the weights for the two machines are approximately normal with 16 degrees of freedom.

	a.	between 0.01 and 0.02
	b.	less than 0.005
	c.	between 0.005 and 0.01
	d.	less than 0.01

6. is an unbiased statistic that is used to estimate mu1 - mu2.
   a. True
   b. False

7. Data collected below represent (by gender) the number and percent of students that reported choosing a healthy item of food. Use alpha level of .05 to determine if a fewer percentage of males chose healthy items as compared to females. Choose the conclusion.

Gender	n	Percent choosing to eat healthy items
p1 Males	475	47%
p2 Females	525	53%

		a. We reject the null hypothesis, males are choosing healthy items less frequently than females.
		b. We reject the null hypothesis, males are Not choosing healthy items less frequently than females.
		c. We fail to reject the null hypothesis, males are choosing healthy items less frequently than females.
		d. We fail to reject the null hypothesis, males are Not choosing healthy items less frequently than females.

8. Samples from two independent, normally-distributed populations produced the following results.

	Population 1	Population 2
Sample size	8	7
Sample mean	13.9	14.3
Sample standard deviation	6.9	5.4

Calculate the test statistic for the difference between population means, .

	a.	–0.126
	b.	–0.058
	c.	–0.107
	d.	–0.04

Answer 1