# Ans Doc246Y

22. Jacob Lee is a frequent traveler between Los Angeles and San Francisco. For the past month, he wrote down the flight times on three different airlines. The results are:
Goust: 51, 51, 52, 42, 51, 57, 47, 47, 50, 60, 54, 49, 48, 48
Jet Red: 50, 53, 52, 62, 53, 49, 50, 49, 58, 54, 51, 49, 49, 50
Cloudtran: 52, 55, 60, 64, 61, 49, 49
a.  use the .05 significance level and the five-step hypothesis-testing process to check if there is a difference in the mean flight times among the three airlines.
b. Develop a 95% confidence interval for the difference in the means between Goust and Cloudtran

28.Three assembly lines are used to produce a certain component for an airliner. To examine the production rate, a random sample of six hourly periods is chosen for each assembly line and the number of components produced during these periods for each line is recorded. The output from a statistical software package is:
Summary:
Groups: Count: Sum: Average: Variance:
Line A 6 250 41.66667 .266667
Line B 6 260 43.33333 .666667
Line C 6 249 41.5 .7
ANOVA
Source of Variation SS df MS F p-value
Btw Groups 12.333 2 6.166 11.32653 .001005
within groups 8.16667 15 .544
Total 20.5 17
a. Use a .01 level of significance to test if there is a difference in the mean production of the three assembly lines.
b. Develop a 99% confidence interval for the difference in the means between Line B and Line C

19. A consumer analyst collected the following data on the screen sizes of popular LCD televisions sold recently at a large number
Manufacturer Screen Price
Sharp 46 1473.00
Samsung 52 2300.00
Samsung 46 1790
Sony 40 1250
Sharp 42 1546.5
Samsung 46 1922.5
Samsung 40 1372.00
Sharp 37 1149.5
Sharp 46 2000.00
Sony 40 1444.5
Sony 52 2615.00
Samsung 32 747.5
Sharp 37 1314.5
Sharp 32 852.5
Sharp 52 2950.00
Samsung 40 1749.5
Sharp 32 1035.00
Samsung 52 2950
Sony 40 1908.5
Sony 52 3103.00
SOny 46 2606
Sony 46 2861
Sony 52 3434
a. Does there appear to be a linear relationship between the screen size and the price?
b. Which variable is the dependent variable?
c. Using statistical software determine the regression equation. Interpret the value of the slope in the regression equation.
d. Include the manufacturer in a multiple linear regression analysis using a “dummy” variable. Does it appear that some manufacturers can command a premium price?
e. Test each of the individual coefficients to see if they are significant.
f. Make a plot of the residuals and comment on whether they appear to follow a normal distribution.
g. Plot the residuals versus the fitted values. Do they seem to have the same amount of variation?