Question

A battery manufacturer advertises that the mean reserve capacity of a certain battery is 1500 hours. You suspect that the batteries’ reserve time is less than the advertised value. To test this claim, you randomly select a sample of 20 batteries and find the mean reserve capacity to be 1320 hours. Assume that the population standard deviation is 320 hours. Do you have enough evidence to support the manufacturer’s claim? What assumption is necessary for this test to be valid?

A. None. The Central Limit Theorem makes any assumptions unnecessary.

B. The population of all the batteries’ reserve time is normally distributed because of the small sample size.

C. The population variance must equal the population mean.

Answer #1

Ans :

B. The population of all the batteries’ reserve time is normally distributed because of the small sample size.

A manufacturer claims that the mean life time of its lithium
batteries is 1500 hours . A home owner selects 30 of these
batteries and finds the mean lifetime to be 1470 hours with a
standard deviation of 80 hours. Test the manufacturer's claim.
Use=0.05. Round the test statistic to the nearest thousandth.
a) Hypothesis:
b)Critical value (t critical):
c)Test statistic (tstat) and the decision about the test
statistic:(reject or fail to reject Ho):
d)Conclusion that results from the decision...

Employees in a large accounting firm claim that the mean salary
of the firm’s accountants is less than that of its competitor’s
which is $45,000. A random sample of 16 of the firm’s accountants
has a mean salary of $43,500. Assume that the population standard
deviation is $5200. Test the employees claim. What assumption is
necessary for this test to be valid?
None. The Central Limit Theorem makes any assumptions
unnecessary.
The population of all salaries of the firm’s accountants...

A manufacturer claims that the mean lifetime of its lithium
batteries is less than 1500 hours. A homeowner selects 25 of these
batteries and finds the mean lifetime to be 1480 hours with a
standard deviation of 80 hours. Test the manufacturer's claim.
Use α = 0.10.
A.
P-value = 0.112 > 0.10; do not reject H0; There is not enough
evidence support the claim, that mean is less than 1500.
B.
P-value = 0.112 > 0.05; do not reject...

1. A manufacturer claims that the mean lifetime of its
fluorescent bulbs is 1500 hours. A homeowner selects 40 bulbs and
finds the mean lifetime to be 1480 hours with a population standard
deviation of 80 hours. Test the manufacturer's claim. Use alpha
equal to 0.05. State the sample mean and the population standard
deviation.
2. Using problem in number 1. Choose the correct hypotheses.
3. Using the problem in number 1. State the critical
value(s).
4. Using the problem...

A company claims that the mean battery life of their MP3
players at least 30 hours. You suspect this claim is incorrect and
find that a random sample of 18 MP3 players has a mean battery life
of 28.5 hours and a standard deviation of 1.7 ours. Is there enough
evidence to reject the claim at α=0.01?
Find the standardized test statistics t
Decide whether to reject or fail to reject the null
hypothesis

A company claims that the mean battery life of their MP3 player
is = 30 hours. You suspect this claim is incorrect and find a
random sample of 18 MP3 players has a mean battery life of 28.5
hours and a standard deviation of 7 hours. Is there enough evidence
to reject the null hypothesis
a=0.01? Ho:
u=30 Ha: not = 30.

A manufacturer claims that the mean lifetime of its fluorescent
bulbs is 1500 hours. A homeowner selects 40 bulbs and finds the
mean lifetime to be 1490 hours with a population standard deviation
of 80 hours. Test the manufacturers claim. Use a=0.05. Show graph
as well.

1. The life in hours of a battery is normally distributed with σ
= 1.25 hours. A random sample of 10 batteries has a mean life of
40.6 hours. Is there evidence to support the claim that battery
life exceeds 40 hours? Use α = 0.05. You may use the traditional or
P-value method.
2. Repeat exercise #1 if we do not know σ, but estimate the
population S.D. using s = 1. Use the traditional method.

40. A cell phone manufacturer claims that its phone will last
for more than 8 hours of continuous talk time when the battery is
fully charged. To test this claim at a 10% level of significance,
a random sample of 18 phones were selected. The results showed a
sample mean of 8.2 hours and a sample standard deviation of 0.4
hour.
Based on the data and hypothesis test, can you dispute the cell
phone manufacturer’s claim?
A.
YES
B.
NO...

A certain type of battery is said to last for 2000hours. A
sample of 200 of these batteries were tested; the mean life was
1995 hours and the standard deviation of the lives was 25.5 hours.
Use these data to test the hypothesis that the population mean life
is 2000 hours against the alternative that it is less than 2000
hours. State the level of significance you are using in your
test.

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