Question

PLEASE ANSWER ALL FIVE QUESTIONS

Question 21

When doing statistical studies collecting more data or having a larger sample size is:

a) Better

b) Problematic

c) Less Expensive

d) Clausistic

QUESTION 24

A sample of 2000 union members was selected and their opinions regarding a proposed management union contract were recorded. 1,600 members were in favor of it. A 95% confidence interval for the population proportion was computed to be 0.78 and 0.82.

a) This indicates that exactly 80 out of 100 similarly constructed intervals would include the population proportion.

b) We are 95% confident that the population proportion (the percentage of union members that would vote for the proposed union contract) is between .78 (78%) and .82 (82%).

c) This information is inconclusive

d) We should state affirmatively that the election would be successful if an 80% vote in favor was necessary for passage

QUESTION 27

If a you want to investigate the tread life of your company’s tires, and you took a sample of 10 tires and constructed a 95% confidence interval, degrees of freedom and t value would be

a) 11 degrees of freedom and t value of 2.201

b) 10 degrees of freedom and t value of 2.228

c) 9 degrees of freedom and t value of 2.262

d) This is a trick question, you can use the Z table with samples of less than 30

QUESTION 28

When the population standard deviation is unknown AND the sample size is less than 30, the test statistic to use is:

a) The Student's t distribution

b) The Binomial Distribution.

c) The Z distribution.

d) Chi-Square

QUESTION 30

What are the factors that determine the size of a sample?

a) The degree of confidence selected.

b) The maximum allowable error.

c) The variation in the population

d) All of the above.

Answer 1

Question 21

Ans(d) Claussistic

A larger sample may help give more accurate results but more samp;e may be more expensive to observe. Hence an appropriate optimum sample size is necessary which gives results with a certain level of accuracy and at the same time, aren't too expensive to collect.

Question 24

Ans(b) We are 95% confident that the population proportion (the percentage of union members that would vote for the proposed union contract) is between .78 (78%) and .82 (82%).

This is comprehended from the definition of a confidence interval for population proportion.

Question 27

Ans(c) 9 degrees of freedom and t value of 2.262

The test statistic has t-istribution with df = n - 1 = 10 - 1 = 9 and for alpha = 0.05 and df = 9, the critical value as seen from table is 2.262

Question 28

Ans (a) The Student's t distribution

As the population standard deviation is not known, t-distribution is the one to go for. Also, as the sample size is less than 30, Z distribution (approximation) cannot be used.

Question 30

Ans (d) All of the above.

The formula for the optimum sample size, say for population mean is given by

Therefore, option (d) is correct.

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