Question

1. Twelve pairs of identical twins that were separated at birth are reunited at age 21. Each twin is weighed. Of interest is if identical twins raised separately will weigh within 10 pounds of each other as young adults. The sample average difference was 12.1 pounds with a standard deviation of 3.4 pounds. If we conduct a hypothesis test, the distribution to use is ______________.

a. Normal
b. Binomial
c. Student-t with df = 24
d. Student-t with df = 11

2. Forty cars from two different models of a car manufacturer are compared to see if the smaller model has a higher average MPG than the larger model. From years of testing these models, it is known that the standard deviation of MPG is 3.4 MPG for the smaller model and 3.6 MPG for the larger one. From this survey, the sample means and standard deviations are 28.2 and 3.5, and 22.6 and 3.7, respectively. The hypothesis test to use is ______________.

a. two proportions
b. independent group means, population standard deviations known
c. matched or paired samples
d. independent group means, population standard deviations unknown

3. Thirty children and forty-five adults were surveyed to determine if children watch, on average, the same amount of television as adults per day. The averages from the study were 3.4 and 2.7 hours per day, respectively. The standard deviations from the study were 2.3 and 1.4 hours per day, respectively. The hypothesis test to use is ______________.

a. matched or paired samples
b. two proportions
c. independent group means, population standard deviations unknown
d. independent group means, population standard deviations known

4. Twelve pairs of identical twins that were separated at birth are reunited at age 21. Each twin is weighed. Of interest is if identical twins raised separately will weigh within 10 pounds of each other as young adults. The hypothesis test to use is ______________.

a. independent group means, population standard deviations unknown
b. independent group means, population standard deviations known
c. matched or paired samples
d. two proportions

5. One hundred men and one hundred women are surveyed to determine if the percent of women that lie about their weight is the same as the percent of men, or if the percent of women is higher than the percent of men. The hypothesis test to use is ______________.

a. independent group means, population standard deviations known
b. two proportions
c. independent group means, population standard deviations unknown
d. matched or paired samples

Answer 1

Solution :

1.

n = 12 , df = 12 - 1 = 11

d bar = 12.1 pounds Sd = 3.4 pounds.

The data is collected for pair. Hence pair t test need to run.

If we conduct a hypothesis test, the distribution to use is ______________.
d. Student-t with df = 11

2.

n1 = n2 = 40

Claim : the smaller model has a higher average MPG than the larger model.
σ1 = 3.4 MPG, σ2 = 3.6 MPG

x̄1 = 28.2 and x̄2 = 3.5, and s1 = 22.6 and s2 = 3.7,

Here samples are collected independantly with n1 > 30 , n2 > 30 and polulation standard deviation known.

The hypothesis test to use is ______________.
b. independent group means, population standard deviations known

3.

n1 = 30 , n2 = 45 , x̄1 = 3.4 and x̄2 = 2.7, and s1 = 2.3 and s2 = 1.4

The hypothesis test to use is ______________.
c. independent group means, population standard deviations unknown

4. n =12  

paired data is collected.

The hypothesis test to use is ______________.
c. matched or paired samples

5.

Proportion of men and women need to compair.

The hypothesis test to use is ______________.

b. two proportions