In 2015, the average duration of long-distance telephone calls from a certain town was 3.9 minutes. A telephone company wants to perform a test to determine whether this average duration of long- distance calls has changed. Fifty calls, originating from the town, was randomly selected and the following summary minutes. Σx= 205 E(x - x)? = 56.43 a) Calculate the sample mean, x. b) Calculate the sample standard deviation c) Using the p value approach at the 1% level of significance, test whether the mean duration of long-distance calls from the town had increased. d) Construct the 99% confidence interval for the population mean duration of the long-distance calls from the town.

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
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Chapter10: Statistics
Section10.5: Comparing Sets Of Data
Problem 13PPS
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In 2015, the average duration of long-distance telephone calls from a certain town was 3.9 minutes.
A telephone company wants to perform a test to determine whether this average duration of long-
distance calls has changed. Fifty calls, originating from the town, was randomly selected and the
following summary minutes.
Σχ= 205
E(x – x)? = 56.43
a) Calculate the sample mean, x.
b) Calculate the sample standard deviation
c) Using the p value approach at the 1% level of significance, test whether the mean duration of
long-distance calls from the town had increased.
d) Construct the 99% confidence interval for the population mean duration of the long-distance
calls from the town.
Transcribed Image Text:In 2015, the average duration of long-distance telephone calls from a certain town was 3.9 minutes. A telephone company wants to perform a test to determine whether this average duration of long- distance calls has changed. Fifty calls, originating from the town, was randomly selected and the following summary minutes. Σχ= 205 E(x – x)? = 56.43 a) Calculate the sample mean, x. b) Calculate the sample standard deviation c) Using the p value approach at the 1% level of significance, test whether the mean duration of long-distance calls from the town had increased. d) Construct the 99% confidence interval for the population mean duration of the long-distance calls from the town.
A random sample of residents from various income brackets were asked their opinion on tax reform
for the country of Guyana. The data so gathered were analyzed by a statistician and the results he
obtained using MINITAB are shown below:
Expected counts are printed below observed counts
Low
Middle
High
Total
For
26
75
14
115
(30.67)
(51.11)
(33.22)
Against
60
95
105
260
(69.33)
(115.56)
(**)
Neutral
34
30
11
75
(33.33)
200
(20)
(21.67)
Total
130
450
Chi-sq =
0.71 +
11.17 +
11.12 +
3.66 +
0.33 +
*** +
11.89 +
9.8 +
5.25 =
55.2
DF = ??, p-value =???
a) Carefully define the null and alternative hypotheses of the x2 test underlying the generation
of the above table.
b) Find the missing values *, **, *****, ??" and ???'.
c) What is the conclusion of this test? Give reasons for your answer.
Transcribed Image Text:A random sample of residents from various income brackets were asked their opinion on tax reform for the country of Guyana. The data so gathered were analyzed by a statistician and the results he obtained using MINITAB are shown below: Expected counts are printed below observed counts Low Middle High Total For 26 75 14 115 (30.67) (51.11) (33.22) Against 60 95 105 260 (69.33) (115.56) (**) Neutral 34 30 11 75 (33.33) 200 (20) (21.67) Total 130 450 Chi-sq = 0.71 + 11.17 + 11.12 + 3.66 + 0.33 + *** + 11.89 + 9.8 + 5.25 = 55.2 DF = ??, p-value =??? a) Carefully define the null and alternative hypotheses of the x2 test underlying the generation of the above table. b) Find the missing values *, **, *****, ??" and ???'. c) What is the conclusion of this test? Give reasons for your answer.
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