A legislative aide is doing research on the duration of calls initiated on cell phones. A...
A legislative aide is doing research on the duration of calls initiated on cell phones. A preliminary study showed that the standard deviation of these calls is 1.7 minutes. "How large a sample" is needed for the aide to state with 99% confidence that the sample mean duration time for the calls differs from the population by no more than .2 minutes.
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A legislative aide is doing research on the duration of calls
initiated on cell phones. A...
A random sample of 41 calls initiated on cellular phones had a mean duration of 3.5...
A random sample of 41 calls initiated on cellular phones had a mean duration of 3.5 minutes. Find a 90% confidence interval for the mean duration of telephone calls initiated on a cellular phone. Assume the population standard deviation is 1.2 minutes
1. A random sample of 50 calls initiated on cell car phones had a mean duration...
1. A random sample of 50 calls initiated on cell car phones had a mean duration of 3.5 Assume the population SD 671.2 min. a) Find a 95% confidence interval for the population mean duration of telephone calls initiated on cell car phone and interpret your result ) Find a 90% confidence interval for the population mean duration of telephone calls itiated on cell car phone. Compare with the result in part a)
Suppose that a phone company reports that the average duration of a cell phone call is...
Suppose that a phone company reports that the average duration of a cell phone call is 1.7 minutes, with a standard deviation of 1.4 minutes. 1. Would it be reasonable to use a normal distribution to model the duration of cell phone calls? Explain, based primarily on the values reported above. 2. Suppose you want to examine a random sample of 60 cell phone calls. Do you think it would be reasonable to use the Central Limit Theorem to describe...
In a random sample of eight cell phones, the mean full retail price was $559.00 and...
In a random sample of eight cell phones, the mean full retail price was $559.00 and the standard deviation was $226 00. Assume the population is normally distributed and use the t-distribution to find the margin of error and construct a 99% confidence interval for the population mean Interpret the results o Identify the margin of error (Round to one decimal place as needed) Construct a 99% confidence interval for the population mean IA (Round to one decimal place as...
Suppose a phone company reports that the average duration of phone calls is 1.7 minutes, with...
Suppose a phone company reports that the average duration of phone calls is 1.7 minutes, with standard deviation of 1.4 minutes. Now suppose that you want to examine a random sample of 60 phone calls. Do you think it would be reasonable to use the Central Limit Theorem to describe the sampling distribution of the sample mean call duration? a. Yes, the CLT applies because the standard deviation is smaller than the mean. b. Yes, the CLT applies because both...
In a random sample of eight cell phones, the mean full retail price was $460.00 and...
In a random sample of eight cell phones, the mean full retail price was $460.00 and the standard deviation was $173.00. Assume the population is normally distributed and use the t-distribution to find the margin of error and construct a 95% confidence interval for the population mean u. Interpret the results. Identify the margin of error. (Round to one decimal place as needed.) Construct a 95% confidence interval for the population mean. (Round to one decimal place as needed.) Interpret...
In a random sample of 7 cell phones, the mean full retail price was $502.40 and...
In a random sample of 7 cell phones, the mean full retail price was $502.40 and the standard deviation was $190.00 Further research suggests that the population mean is $427.17. Does the t-value for the original sample fall between −t 0.99 and t 0.99? Assume that the population of full retail prices for cell phones is normally distributed.
Cell Phone Lifetimes A recent study of the lifetimes of cell phones found the average is...
Cell Phone Lifetimes A recent study of the lifetimes of cell phones found the average is 24.3 months. The standard deviation is 2.6 months. If a company provides its 32 employees with a cell phone, find the probability that the mean lifetime of these phones will be less than 23.7 months. Assume cell phone life is a normally distributed variable, the sample is taken from a large population and the correction factor can be ignored. Round the final answer to...
inutes, The duration of telephone calls directed by the local telephone company: s 3.8 m 100,...
inutes, The duration of telephone calls directed by the local telephone company: s 3.8 m 100, confidence interval 98%. 4. The mean replacement time for a random sample of 20 machines is 7.5 years and the standard deviation is 2.4 years. Construct a 99% confidence interval for the standard deviation , σ , of a replacement time of all washing machines of this type (user distribution for analysis)
In a random sample of eleven cell phones, the mean full retail price was $515.50 and...
In a random sample of eleven cell phones, the mean full retail price was $515.50 and the standard deviation was $212.00. Assume the population is normally distributed and use the t-distribution to find the margin of error and construct a 90% confidence interval for the population mean mu. Interpret the results.
1. A random sample of 50 calls initiated on cell car phones had a mean duration of 3.5 Assume the population SD 671.2 min. a) Find a 95% confidence interval for the population mean duration of telephone calls initiated on cell car phone and interpret your result ) Find a 90% confidence interval for the population mean duration of telephone calls itiated on cell car phone. Compare with the result in part a)
In a random sample of eight cell phones, the mean full retail price was $559.00 and the standard deviation was $226 00. Assume the population is normally distributed and use the t-distribution to find the margin of error and construct a 99% confidence interval for the population mean Interpret the results o Identify the margin of error (Round to one decimal place as needed) Construct a 99% confidence interval for the population mean IA (Round to one decimal place as...
In a random sample of eight cell phones, the mean full retail price was $460.00 and the standard deviation was $173.00. Assume the population is normally distributed and use the t-distribution to find the margin of error and construct a 95% confidence interval for the population mean u. Interpret the results. Identify the margin of error. (Round to one decimal place as needed.) Construct a 95% confidence interval for the population mean. (Round to one decimal place as needed.) Interpret...
inutes, The duration of telephone calls directed by the local telephone company: s 3.8 m 100, confidence interval 98%. 4. The mean replacement time for a random sample of 20 machines is 7.5 years and the standard deviation is 2.4 years. Construct a 99% confidence interval for the standard deviation , σ , of a replacement time of all washing machines of this type (user distribution for analysis)
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