Question

2.) A telephone company claims that 20% of its customers have at least two telephone lines. The company selects a random sample of 500 customers and finds that 88 have two or more telephone lines. At a α = 0.05 significance level, can you conclude that the proportion of customers having at least two telephone lines isn’t 20%?

Answer #1

A manufacturer claims that the calling range (in feet) of its
900-MHz cordless telephone is greater than that of its leading
competitor. A sample of 6 phones from the manufacturer had a mean
range of 1300 feet with a standard deviation of 20 feet. A sample
of 12 similar phones from its competitor had a mean range of 1290
feet with a standard deviation of 42 feet. Do the results support
the manufacturer's claim? Let μ1 be the true mean...

2. A shopping center developer claims in a presentation to a
client that at least 40% of the adult female population in a
community visit the mall one or more times in a week. To evaluate
this claim, a research firm selects a random sample of 200 adult
females from the community and finds that 70 of the 200 say that
they visit the mall one or more times in a week. Does this data
provide enough evidence to disprove...

A local telephone company claims that the average length of a
phone call is 8 minutes in a random sample of 18 calls. The sample
mean was 7.8 minutes and sample standard deviation was 0.5 minutes.
Is there enough evidence to support the company’s claim at
α=0.05.

A manufacturer claims that the calling range (in feet) of its
900-MHz cordless telephone is greater than that of its leading
competitor. A sample of 17 17 phones from the manufacturer had a
mean range of 1100 1100 feet with a standard deviation of 33 33
feet. A sample of 10 10 similar phones from its competitor had a
mean range of 1090 1090 feet with a standard deviation of 42 42
feet. Do the results support the manufacturer's claim?...

A marketing company claims that it receives more than 6.5%
responses from its Mailing. A sample of 600 mails yesterday
revealed 54 responses. At the 0.05 level of significance, can we
conclude that the claim is true?

A manufacturer claims that the calling range (in feet) of its
900-MHz cordless telephone is greater than that of its leading
competitor. A sample of 18 phones from the manufacturer had a mean
range of 1250 feet with a standard deviation of 31 feet. A sample
of 11 similar phones from its competitor had a mean range of 1230
feet with a standard deviation of 33 feet. Do the results support
the manufacturer's claim? Let μ 1 be the true...

A manufacturer claims that the calling range (in feet) of its
900-MHz cordless telephone is greater than that of its leading
competitor. A sample of 21 phones from the manufacturer had a mean
range of 1140 feet with a standard deviation of 43 feet. A sample
of 11 similar phones from its competitor had a mean range of 1110
feet with a standard deviation of 38 feet. Do the results support
the manufacturer's claim? Let μ1 be the true mean...

The CEO of a large electric company claims that 80 % of his
1,000,000 customers are very satisfied with the service they
receive. To test this claim, the local newspaper surveyed a random
sample of 500 customers. Among the sampled customers, only 380 said
they are very satisfied. Is this evidence that the CEOs. claim is
false, and less than 80% of customers are very satisfied? Suppose
that, in fact, 77% of customers are satisfied. Using a significance
level of...

With individual lines at its various windows, a post office
finds that the standard deviation for normally distributed waiting
times for customers on Friday afternoon is 7.2 minutes. The post
office experiments with a single, main waiting line and finds that
for a random sample of 25 customers, the waiting times for
customers have a standard deviation of 3.5 minutes.
With a significance level of 5 percent, test the claim that a
single line causes lower variation among waiting times...

A manufacturer claims that the calling range (in feet) of its
900-MHz cordless telephone is greater than that of its leading
competitor. A sample of 11 phones from the manufacturer had a mean
range of 1070 feet with a standard deviation of 25 feet. A sample
of 17 similar phones from its competitor had a mean range of 1040
feet with a standard deviation of 22 feet. Do the results support
the manufacturer's claim? Let μ1 be the true mean...

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