# Chapter 9 Quize

**Topics:**Normal distribution, Confidence interval, Standard deviation

**Pages:**17 (3222 words)

**Published:**April 25, 2013

INTERVAL ESTIMATION

MULTIPLE CHOICE QUESTIONS

In the following multiple choice questions, circle the correct answer.

1.When s is used to estimate (, the margin of error is computed by using a.normal distribution

b.t distribution

c.the mean of the sample

d.the mean of the population

Answer: b

2.As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution

a.becomes larger

b.becomes smaller

c.stays the same

d.None of these alternatives is correct.

Answer: b

3.For the interval estimation of ( when ( is known and the sample is large, the proper distribution to use is

a.the normal distribution

b.the t distribution with n degrees of freedom

c.the t distribution with n + 1 degrees of freedom

d.the t distribution with n + 2 degrees of freedom

Answer: a

4.An estimate of a population parameter that provides an interval of values believed to contain the value of the parameter is known as the

a.confidence level

b.interval estimate

c.parameter value

d.population estimate

Answer: b

5.The value added and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the

a.confidence level

b.margin of error

c.parameter estimate

d.interval estimate

Answer: b

6.If an interval estimate is said to be constructed at the 90% confidence level, the confidence coefficient would be

a.0.1

b.0.95

c.0.9

d.0.05

Answer: c

7.Whenever the population standard deviation is unknown and the population has a normal or near-normal distribution, which distribution is used in developing an interval estimation?

a.standard distribution

b.z distribution

c.alpha distribution

d.t distribution

Answer: d

8.In interval estimation, the t distribution is applicable only when

a.the population has a mean of less than 30

b.the sample standard deviation is used to estimate the population standard deviation

c.the variance of the population is known

d.the standard deviation of the population is known

Answer: b

9.In developing an interval estimate, if the population standard deviation is unknown

a.it is impossible to develop an interval estimate

b.the standard deviation is arrived at using the range

c.the sample standard deviation can be used

d.it is assumed that the population standard deviation is 1

Answer: c

10.In order to use the normal distribution for interval estimation of ( when ( is known and the sample is very small, the population

a.must be very large

b.must have a normal distribution

c.can have any distribution

d.must have a mean of at least 1

Answer: b

11.From a population that is not normally distributed and whose standard deviation is not known, a sample of 6 items is selected to develop an interval estimate for the mean of the population (().

a.The normal distribution can be used.

b.The t distribution with 5 degrees of freedom must be used.

c.The t distribution with 6 degrees of freedom must be used.

d.The sample size must be increased.

Answer: d

12.A sample of 200 elements from a population is selected, and the standard deviation of the sample is computed. For an interval estimation of (, the proper distribution to use is the

a.normal distribution

b.t distribution with 200 degrees of freedom

c.t distribution with 201 degrees of freedom

d.t distribution with 202 degrees of freedom

Answer: a

13.From a population that is normally distributed, a sample of 25 elements is selected and the standard deviation of the sample is computed. For the interval estimation of (, the proper distribution to use is the

a.normal distribution

b.t distribution with 25 degrees of freedom

c.t distribution with 26 degrees of freedom

d.t distribution...

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