Share
Explore BrainMass

Multiple choice questions- Hypothesis testing

I'm having trouble understanding the following question can you please explain?

1) The owner of an Internet video supplier, Netflix, has conducted a study of habits of online customers. In particular she wants to estimate the average number of videos checked out each month. Before she can determine the sample size she will need, she needs to make an estimate of the standard deviation. On the basis of her past experience and judgment, she estimate that the standard deviation is equal to 12. Suppose that a pilot study of 15 online customers indicates a sample standard deviation of 9.25 videos. At 0.10 level of significance what are the critical boundaries for rejecting H : @=12
0
A)x2 <-6.571 or x2 >+ 6.571 (B) x2<-6.571 or x2 >+23.685 (C) x2 <-2.575 or x2 >+2.575(D) x2 <-23.865 or x2 > + 23.685

2) A survey claims that 9 out of 10 doctors recommend aspirin for their patient with headaches. To test this claim against the alternative that the actual proportion of doctors who recommend aspirin is less than 0.90, a random sample of 100 doctors results in 83 who indicate that they recommend aspirin. The value of the test statistic in this problem is approximately equal to:
A) -4.12 (B) -2.33 (C) -1.86 (D) -0.07

3) Using the table below, which of the following is the correct calculation of the t statistic needed to test the null hypothesis that there is no difference in the average price of items at two stores?

ITEM STORE A STORE B
1gal milk $2.94 $3.33
Tide Detergent, jumbo box 7.58 8.79
3lbs. Fuji apple 2.41 2.97
Oreo 3.16 3.39
1lb T-bone 5.77 7.99
Tropicana OJ, 64 oz 3.67 3.99
Huggies 24 pack 7.76 7.99
1pint Breyers ice cream 2.94 3.19
64oz Colgate toothpaste 2.08 2.19

A) -0.011 (B) -0.541 (C) -1.746 (D) -2.686

4) If the p value is less than a in two-tailed test
A) the null hypothesis (B) the null hypothesis should be rejected (C) a one-tailed test should be used(D) no conclusion should be reached

5) Calculate the test statistic for the internet video supplier's research in Problem #12 above. The test statistic, x2 =
A) Cannot be computed because the population standard deviation is not known (B) 8.913 (C) 8.319 (D) -8.913

6) An upholstery business is studying differences between two of its major outlet stores in the time its take customers to receive furniture that was custom ordered. The following data shows a sample of delivery times for the most popular types of furniture.

STORE A STORE B
X 34.3 days 43.7 days
S 2.4 days 3.1 days
n 41 31

Which of the following is the correct F statistic for testing the equality of the variance for these two sample.
A) 0.599 (B) 0.774 (C) 0.935 (D) 1.018

7) Assembly line worker are randomly assigned to two groups with 21 workers in each group. Each group receive a different training program and then their scores on an assembly task are compared. The F statistic for the variance in 2 groups is 0.178. Using a 0.05 level of significance, what are the critical values for rejecting the null hypothesis that there is no difference in the variance of these two population?
A) If F < 2.46 and F>0.407, rejects H ( B) if F >2.46 or F< 0.407, rejects H
0 0
C) If F < 2.12 and F> 0.472 rejects H (D) If > 2.12 or F< 0.472 rejects H
0 0

8) For a given sample size n, if the level of significance (a) is decreased, the power of the test :
A) will increase (B) will decrease (C) will remain the same (D) cannot be determined

9) In what type of test is the variable of interest the difference between the value of the observation rather than the observation themselves.
A) A test for equality of variance from two independent population (B) A test for difference between the means of two related population (C) A test for the difference between the means of two independent population (D) all of the above

10) In testing for differences between the means of two related populations, the null hypothesis is:
A) H: u =2 (B) H: u < 0 (C) H : u (D) H : u = 0
0 D 0 D 0 D 0 D

11) How many Kleenex should the Kimberly Clark Corporation package of issue contain? Researchers determined that 60 tissue is the average number of tissues used during a cold. Suppose a random sample of 100 Kleenex users yielded the following data on the number of tissue used during a cold:-- = 52,s=22. Using the sample information
X
provided, calculate the value of the test statistic.
A) t=-0.3636 (B) t=-36.3636(C)t=-3636.3636 (D) t=-3.6364

Attachments

Solution Preview

1) The owner of an Internet video supplier, Netflix, has conducted a study of habits of online customers. In particular she wants to estimate the average number of videos checked out each month. Before she can determine the sample size she will need, she needs to make an estimate of the standard deviation. On the basis of her past experience and judgment, she estimate that the standard deviation is equal to 12. Suppose that a pilot study of 15 online customers indicates a sample standard deviation of 9.25 videos. At 0.10 level of significance what are the critical boundaries for rejecting H : &#963;=12

A)x2 <-6.571 or x2 >+ 6.571 (B) x2<-6.571 or x2 >+23.685 (C) x2 <-2.575 or x2 >+2.575(D) x2 <-23.865 or x2 > + 23.685

Answer: (B) x2<6.571 or x2 >+23.685

n= 15
degrees of freedom=n-1= 14 =15-1
&#945;= 0.1
0r Confidence level of 90%
Corresponding to this confidence level and degrees of freedom the chi square values are
&#935;L 2 = 6.571 corresponding to area in the right tail of 0.95
&#935;U 2 = 23.685 corresponding to area in the right tail of 0.05

Rejection region: > 23.685
< 6.571

2) A survey claims that 9 out of 10 doctors recommend aspirin for their patient with headaches. To test this claim against the alternative that the actual proportion of doctors who recommend aspirin is less than 0.90, a random sample of 100 doctors results in 83 who indicate that they recommend aspirin. The value of the test statistic in this problem is approximately equal to:
A) -4.12 (B) -2.33 (C) -1.86 (D) -0.07

Answer: (B) -2.33

hypothesized proportion=p= 0.90
q=1-p= 0.10
n=sample size= 100
&#963;p=standard error of proportion=&#8730;(pq/n)= 0.03 =&#8730; ( .9 x .1 / 100)
sample proportion= 0.83 =83/100
z=(sample proportion-hypothesized proportion)/&#963;p -2.33 =(0.83-0.9)/0.03

3) Using the table below, which of the following is the correct calculation of the t statistic needed to test the null hypothesis that there is no difference in the average price of items at two stores?

ITEM STORE A STORE B
1gal milk $2.94 ...

Solution Summary

Multiple choice questions on hypothesis testing-related with rejecting/ accepting Null Hypothesis, t statistic , p-value, two tailed test, population standard deviation, equality of the variance, F statistic, power of test, related populations etc are answered.

$2.19