Question

A research council wants to estimate the mean length of time (in minutes) that the average U.S. adult spends watching television using digital video recorders (DVR’s) each day. To determine the estimate, the research council takes random samples of 35 U.S. adults and obtains the following times in minutes.

24 |
27 |
26 |
29 |
33 |

21 |
18 |
24 |
23 |
34 |

17 |
15 |
19 |
23 |
25 |

29 |
36 |
19 |
18 |
22 |

16 |
45 |
32 |
12 |
24 |

35 |
14 |
40 |
30 |
19 |

14 |
28 |
32 |
15 |
39 |

From past studies, the research council has found that the standard deviation time is 4.3 minutes and that the population of times is normally distributed.

Construct a 90% confidence interval for the population mean.

Construct a 99% confidence interval for the population mean.

Interpret the results and compare the widths of the confidence intervals.

Test the claim that the mean time spent watching DVR’s is 20 minutes each day using a significance level of 0.05.

You may use a TI-84 calculator or any software you prefer to find the confidence intervals.

Answer #1

The statistical software output for this problem is :

The 90% confidence interval is : **(21.52 ,
26.53)**

The 99% confidence interval is : **(19.99 ,
28.07)**

Fail to reject the null hypothesis .

Claim is not true

A research council wants to estimate the mean length of time (in
minutes) that the average U.S. adult spends watching television
using digital video recorders (DVR’s) each day. To determine the
estimate, the research council takes random samples of 35 U.S.
adults and obtains the following times in minutes.
24
27
26
29
33
21
18
24
23
34
17
15
19
23
25
29
36
19
18
22
16
45
32
12
24
35
14
40
30
19
14...

A publisher wants to estimate the mean length of time? (in
minutes) all adults spend reading newspapers. To determine this?
estimate, the publisher takes a random sample of 15 people and
obtains the results below. From past? studies, the publisher
assumes standard deviation is 1.7 minutes and that the population
of times is normally distributed.
9
10
6
8
11
7
10
8
7
12
12
11
9
9
9
Construct the? 90% and? 99% confidence intervals for the
population...

A publisher wants to estimate the mean length of time (in
minutes) all adults spend reading newspapers. To determine this
estimate, the publisher takes a random sample of 15 people and
obtains the results below. From past studies, the publisher
assumes sigma is 2.7 minutes and that the population of times is
normally distributed. 12 12 6 9 11 12 9 9 11 10 6 6 12 6 6
Construct the 90% and 99% confidence intervals for the population
mean....

A publisher wants to estimate the mean length of time (in
minutes) all adults spend reading newspapers. To determine this
estimate, the publisher takes a random sample of 15 people and
obtains the results below. From past studies, the publisher
assumes sigma is 2.1 minutes and that the population of times is
normally distributed.
6 10 12 6 6 10 7 7 8 8 11 11 9 10 7
Construct the 90% and 99% confidence intervals for the
population mean....

A publisher wants to estimate the mean length of time (in
minutes) all adults spend reading newspapers. To determine this
estimate, the publisher takes a random sample of 15 people and
obtains the results below. From past studies, the publisher
assumes sigma σ is 2.1 minutes and that the population of times is
normally distributed. 6 9 6 11 6 7 10 12 8 6 8 9 10 10 9
Construct the 90% and 99% confidence intervals for the
population...

A publisher wants to estimate the mean length of time (in
minutes) all adults spend reading newspapers. To determine this
estimate, the publisher takes a random sample of 15 people and
obtains the results below. From past studies, the publisher
assumes
sigmaσ
is
2.22.2
minutes and that the population of times is normally
distributed.
99
88
99
1111
66
99
99
77
1212
77
1212
66
99
1212
99
Construct the 90% and 99% confidence intervals for the
population mean....

A publisher wants to estimate the mean length of time (in
minutes) all adults spend reading newspapers. To determine this
estimate, the publisher takes a random sample of 15 people and
obtains the results below. From past studies, the publisher
assumes sigma is 1.9 minutes and that the population of times is
normally distributed. 10 10 8 10 10 6 10 11 7 9 7 7 8 12 11
Construct the 90% and 99% confidence intervals for the population
mean....

publisher wants to estimate the mean length of time (in
minutes) all adults spend reading newspapers. To determine this
estimate, the publisher takes a random sample of 15 people and
obtains the results below. From past studies, the publisher
assumes sigmaσ is1.9 minutes and that the population of times is
normally distributed.
11
7
8
12
7
11
6
6
9
9
7
8
10
8
10
Construct the 90% and 99% confidence intervals for the
population mean. Which interval...

The Buffalo, New York, Chamber of Commerce wants to estimate the
mean time workers who are employed in the downtown area spend
getting to work. A sample of 15 workers reveals the following
number of minutes spent traveling.
14
24
24
19
24
7
31
20
26
23
23
28
16
15
21
Develop a 98% confidence interval for the population mean
Confidence interval is between _________ and _______

You want to estimate the mean time
college students spend watching online videos each day. The
estimate must be within 2 minutes of the population mean. Determine
the required sample size to construct a 99% confidence interval for
the population mean. Assume that the population standard deviation
is 4.4 minutes. Leave as an integer.

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