Question

QUESTION 8

1. [NOTE: The next 8 questions are all different parts of this question].
   
   Before they can be marketed, all new medical devices must be approved by the Food and Drug Administration (FDA). A new device has a protective cover which needs to be removed easily. A similar device, already on the market, has a cover that requires an average force of 8 pounds to remove. The laboratory test data on a random sample of 9 of the new device indicates the following removal forces:
   
       6.3, 8.4, 7.8, 6.4, 5.4, 8.0, 7.0, 6.2, 7.5
   
   Assume that the removal force has a normal distribution with a standard deviation σ =1.2 pounds. Does the data support the conclusion that the new device requires an average removal force less than 8 pounds? When making decision, let the probability of making a type I error be no more than 0.10.
   
   The correct set of null & alternative hypotheses are:

   	a.	Ho: μ ≥ 8     Ha: μ < 8
   	b.	Ho: μ ≤ 8     Ha: μ = 8
   	c.	Ho: μ > 8     Ha: μ ≤ 8
   	d.	Ho: μ < 8     Ha: μ ≥ 8

3 points   

QUESTION 9

1. The significance level of the test is:

   	a.	0.01
   	b.	0.02
   	c.	0.05
   	d.	0.10

2 points   

QUESTION 10

1. The test-statistic appropriate for this test is distributed as a

   	a.	Z random variable.
   	b.	t random variable.
   	c.	Z random variable, but can be approximated as a t.
   	d.	t random variable, but can be approximated as a Z.

3 points   

QUESTION 11

1. The computed value of test statistic equals

   	a.	-2.5
   	b.	2.3
   	c.	-3.0
   	d.	1.80

3 points   

QUESTION 12

1. The critical value of the test is:

   	a.	1.645
   	b.	-1.282
   	c.	-2.576
   	d.	-2.326

2 points   

QUESTION 13

1. The decision is that

   	a.	the alternative hypothesis is rejected. The average removal force is greater than 8 lbs.
   	b.	the alternative hypothesis is accepted. The average removal force is greater than 8 lbs.
   	c.	Not enough information is given to answer this question.
   	d.	the null hypothesis is rejected. The average removal force is less than 8 lbs.

3 points   

QUESTION 14

1. The p-value of the test is:

   	a.	0.0107
   	b.	0.0359
   	c.	0.0013
   	d.	0.0062

3 points   

QUESTION 15

1. Using p-value criterion, the decision is:

   	a.	Reject H0.
   	b.	Fail to reject H0.
   	c.	Reject Ha.
   	d.	Fail to reject Ha.

Answer 1

8)

Ho: μ ≥ 8 Ha: μ < 8

9)

0.10

10)
Z random variable.

11)

z = (xbar - mu)/(sigma/sqrt(n))
= ( 7 - 8)/(1.2/sqrt(9))
= -2.50

12)

Critical avlue = -1.282

13)

the null hypothesis is rejected. The average removal force is less than 8 lbs.

14)

p value = 0.0062

15)

Reject H0