A simple random sample of size n is drawn from a population that is known to be normally distributed. The samplevariance,

s squared

,

is determined to be

12.1

.
Complete parts (a) through (c).

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Part 1

(a) Construct a 90% confidence interval for
sigma squared

if the sample size, n, is 20.

The lower bound is
enter your response here

.
(Round to two decimal places as needed.)

Part 2

The upper bound is
enter your response here

.
(Round to two decimal places as needed.)

Part 3

(b) Construct a 90% confidence interval for
sigma squared

if the sample size, n, is 30.

The lower bound is
enter your response here

.
(Round to two decimal places as needed.)

Part 4

The upper bound is
enter your response here

.
(Round to two decimal places as needed.)

Part 5

How does increasing the sample size affect the width of the interval?

The width increases

The width decreases

The width does not change

Part 6

(c) Construct a 98% confidence interval for
sigma squared

if the sample size, n, is 20.

The lower bound is
enter your response here

.
(Round to two decimal places as needed.)

Part 7

The upper bound is
enter your response here

.
(Round to two decimal places as needed.)

Part 8

Compare the results with those obtained in part (a). How does increasing the level of confidence affect the confidence interval?

The width does not change

The width increases

The width decreases

Transcribed Image Text:A simple random sample of sizen is drawn from a population that is known to be normally distributed. The sample variance, s“, is determined to be 12.1. Complete parts (a) through (c). (a) Construct a 90% confidence interval for o? if the sample size, n, is 20. The lower bound is - (Round to two decimal places as needed.) The upper bound is (Round to two decimal places as needed.) (b) Construct a 90% confidence interval for o2 if the sample size, n, is 30. The lower bound is und to two decimal places as needed.) The upper bound is (Round to two decimal places as needed.) How does increasing the sample size affect the width of the interval? O The width increases The width decreases O The width does not change (c) Construct a 98% confidence interval for o2 if the sample size, n, is 20. The lower bound is (Round to two decimal places as needed.) The upper bound is (Round to two decimal places as needed.)

Question

A simple random sample of size n is drawn from a population that is known to be normally distributed. The samplevariance,

s squared

,

is determined to be

12.1

.

Complete parts (a) through (c).

Question content area bottom

Part 1

(a) Construct a 90% confidence interval for

sigma squared

if the sample size, n, is 20.

The lower bound is

enter your response here

.

(Round to two decimal places as needed.)

Part 2

The upper bound is

enter your response here

.

(Round to two decimal places as needed.)

Part 3

(b) Construct a 90% confidence interval for

sigma squared

if the sample size, n, is 30.

The lower bound is

enter your response here

.

(Round to two decimal places as needed.)

Part 4

The upper bound is

enter your response here

.

(Round to two decimal places as needed.)

Part 5

How does increasing the sample size affect the width of the interval?

The width increases

The width decreases

The width does not change

Part 6

(c) Construct a 98% confidence interval for

sigma squared

if the sample size, n, is 20.

The lower bound is

enter your response here

.

(Round to two decimal places as needed.)

Part 7

The upper bound is

enter your response here

.

(Round to two decimal places as needed.)

Part 8

Compare the results with those obtained in part (a). How does increasing the level of confidence affect the confidence interval?

The width does not change

The width increases

The width decreases

A simple random sample of sizen is drawn from a population that is known to be normally distributed. The sample variance, s“, is determined to
be 12.1. Complete parts (a) through (c).
(a) Construct a 90% confidence interval for o? if the sample size, n, is 20.
The lower bound is
- (Round to two decimal places as needed.)
The upper bound is
(Round to two decimal places as needed.)
(b) Construct a 90% confidence interval for o2 if the sample size, n, is 30.
The lower bound is
und to two decimal places as needed.)
The upper bound is
(Round to two decimal places as needed.)
How does increasing the sample size affect the width of the interval?
O The width increases
The width decreases
O The width does not change
(c) Construct a 98% confidence interval for o2 if the sample size, n, is 20.
The lower bound is
(Round to two decimal places as needed.)
The upper bound is
(Round to two decimal places as needed.)

Accepted Answer

here given sample variance  =  s2 = 12.1

(a) Construct a 90% confidence interval for o? if the sample size, n, is 20. The lower bound is (Round to two decimal places as needed.) The upper bound is (Round to two decimal places as needed.)

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Part 1

Part 2

Part 3

Part 4

Part 5

Part 6

Part 7

Part 8