BUSI 405 Weekly Exercise 2 solutions complete answers
3. Twenty graduate students in business were asked how many credit hours they were taking in the current quarter. Their responses are shown as follows:
a. Determine the mean, median, and mode for this sample of data. Write a sentence explaining what each means.
b. It has been suggested that graduate students in business take fewer credits per quarter than the typical graduate student at this university. The mean for all graduate students is 9.1 credit hours per quarter, and the data are normally distributed. Set up the appropriate null and alternative hypotheses, and determine whether the null hypothesis can be rejected at a 95 percent confidence level.
8. CoastCo Insurance, Inc., is interested in forecasting annual larceny thefts in the United States using the following data:
a. Prepare a time-series plot of these data. On the basis of this graph, do you think there is a trend in the data? Explain.
b. Look at the autocorrelation structure of larceny thefts for lags of 1, 2, 3, 4, and 5. Do the autocorrelation coefficients fall quickly toward zero? Demonstrate that the critical value for rk is 0.417. Explain what these results tell you about a trend in the data.
c. On the basis of what is found in parts a and b, suggest a forecasting method from Table 2.1 that you think might be appropriate for this series.
9. Use exploratory data analysis to determine whether there is a trend and/or seasonality in mobile home shipments (MHS). The data by quarter are shown in the following table:
On the basis of your analysis, do you think there is a significant trend in MHS? Is there seasonality? What forecasting methods might be appropriate for MHS according to the guidelines in Table 2.1?
10. Home sales are often considered an important determinant of the future health of the economy. Thus, there is widespread interest in being able to forecast home sales (HS). Quarterly data for HS are shown in the following table in thousands of units:
a. Prepare a time-series plot of THS. Describe what you see in this plot in terms of trend and seasonality.
b. Calculate and plot the first 12 autocorrelation coefficients for HS. What does this autocorrelation structure suggest about the trend?
11. Exercise 12 of Chapter 1 includes data on the Japanese exchange rate (EXRJ) by month. On the basis of a time-series plot of these data and the autocorrelation structure of EXRJ, would you say the data are stationary? Explain your answer.
