Cheryl Johnson, the director of marketing for the Thingamajig Company, has

collected data on the annual number of households in the state, the adjusted average

annual household income, and Thingamajig's sales of widgets. She would like you to

analyze these data for developing a forecast of future widget sales.

Average

Number of Household Widgets

Year Households Income Sold

$198039\mathrm{.}534,0005,500$

$198139\mathrm{.}834,6005,600$

$198240\mathrm{.}441,0005,900$

$198343\mathrm{.}138,0005,800$

$198443\mathrm{.}239,0006,100$

$198544\mathrm{.}042,0006,900$

$198644\mathrm{.}544,0006,300$

$198746\mathrm{.}249,0007,300$

$198846\mathrm{.}546,0006,700$

$198946\mathrm{.}851,0006,900$

$199047\mathrm{.}048,0007,200$

$199147\mathrm{.}147,0007,100$

$199247\mathrm{.}350,0007,100$

$199347\mathrm{.}751,0007,400$

$199448\mathrm{.}053,0007,600$

$199548\mathrm{.}154,0007,900$

$199648\mathrm{.}455,0007,300$

$199748\mathrm{.}553,0008,000$

$199849\mathrm{.}057,0008,500$

Question #$1$

$1.($A$)$ In sheet Question #$1,$Perform a regression analysis on the above data to see if the

population can be used to predict future sales. $($B$)$ Create a graph that shows the historical data, the

regression line and $95\%$ confidence interval lines. $($C$)$ Predict sales for the next three years based

on the population projections listed below.

$($fill in the blanks below$)$

Estimated

Year Population Prediction

$199952\mathrm{.}0$

$200052\mathrm{.}1$

$200152\mathrm{.}3$

$($D$)$ Is this a good representational model? Why or why not?

$($Answer$)$:

Question #$2$

$2.($A$)$ In sheet Question #$2$ perform a regression analysis on the above data to see if household

income can be used to predict future sales. $($B$)$ Create a graph that shows the historical data, the

regression line and $95\%$ confidence interval lines. $($C$)$ Predict sales for the next three years based

on the income projections listed below.

$($fill in the blanks below$)$

Estimated

Year Income Prediction

$199958,000$

$200062,000$

$200165,000$

$($D$)$ Is this a good representational model? Why or why not?

$($Answer$)$:

Question #$3$

$3.($A$)$ In sheet Question #$3$ perform a multiple regression analysis on the above data to see if household

income and population can be used to predict future sales. $($B$)$ Predict sales for the next three years

based on the income and population projections listed below.

$($fill in the blanks below$)$

Estimated Estimated

Year Income Population Prediction

$199958,00052\mathrm{.}0$

$200062,00052\mathrm{.}1$

$200165,00052\mathrm{.}3$

$($C$)$ Is this a good representational model? Why or why not?

$($Answer$)$: