problem set 7
The data file, CDRates.xlsx, contains the yields for a one-year CD and a five-year CD sold by a randomly selected sample of 46 financial institutions. Use Microsoft Excel to answer the following questions, and upload the results here as an Excel file with the .xlsx extension. Show all your work in the Excel file. (a) Construct a 95% confidence interval estimate for the mean yield of one-year CDs. (b) Construct a 99% confidence interval estimate for the mean yield of one-year CDs. (c) Construct a 95% confidence interval estimate for the mean yield of five-year CDs. (d) Construct a 99% confidence interval estimate for the mean yield of five-year CDs.
"problem set 7 work" excel sheet
An economist is interested in studying the incomes of consumers in a country. The population standard deviation is known to be $1,000. A random sample of 50 individuals resulted in a mean income of $15,000. What is the upper limit in a 99% confidence interval for the population mean income? $15,052 $15,364 $15,330 $15,141
$15,364
A major department store chain is interested in estimating the mean dollar amount its credit card customers spent on their first visit to the chain's new store in the mall. The dollar amount spent on their first visit is normally distributed. Fifteen credit card accounts were selected as a random sample. The sample mean is $50.50, and the sample standard deviation is $20. What is the lower limit of the 95% confidence interval for the population mean? $65.872 $35.128 $39.424 $61.576
$39.424
A major department store chain is interested in estimating the mean dollar amount its credit card customers spent on their first visit to the chain's new store in the mall. The dollar amount spent on their first visit is normally distributed. Fifteen credit card accounts were selected as a random sample. The sample mean is $50.50, and the sample standard deviation is $20. What is the critical t value for 95% confidence? 2.947 2.131 2.145 2.977
2.145
For the Student's t distribution, the size of a randomly selected sample is equal to the degrees of freedom of the sample. True False
False
Holding the level of confidence fixed, increasing the sample size will lead to a wider confidence interval. True False
False
Which of the following is NOT true about a confidence interval estimate for a population parameter? It is an interval constructed such that the probability the interval includes the population parameter is known. It allows us to use a single sample to estimate the population parameter. It is the value of a single sample statistic. It is a range of numbers, called an interval, constructed around the point estimate.
It is the value of a single sample statistic.
Which of the following is NOT true about the Student's t distribution? As the sample size and degrees of freedom increase, the t distribution approaches the standardized normal (Z) distribution. The Z values are more variable than the t values because the sample standard deviation is used to estimate the unknown population standard deviation. It is bell-shaped and symmetrical. It has more area in the tails and less in the center than does the normal distribution.
The Z values are more variable than the t values because the sample standard deviation is used to estimate the unknown population standard deviation.
A 99% confidence interval estimate can be interpreted to mean that we have 99% confidence that the interval constructed from the sample we've selected includes the population mean. True False
True
For a given sample data set, the confidence interval will be wider for 99% confidence than for 95% confidence. True False
True
The Student's t distribution is used to develop a confidence interval estimate of the population mean when the population standard deviation is unknown. True False
True
