# Least-squares method

1. The data below represent the amount of grams of carbohydrates in a serving of breakfast

Cereal for 11 days [15 points]

12, 16, 24, 29, 20, 23, 22, 21, 55, 24, 17

(a) Compute the mean and the median. Interpret the meaning in this problem.

(b) Compute the standard deviation and coefficient of variation. Interpret the meaning in

this problem.

(c) List the five-number summary in this data.

(d)  Form the box-and-whisker plot.

2. A candy bar manufacturer is interested in trying to estimate how sales are influenced by

the price of their product. To do this, the company randomly chooses 6 small cities and

offers the candy bar at different prices. Using candy bar sales as the dependent variable,

the company will conduct a simple linear regression on the data below: [15 points]

City            Price (\$)     Sales

River Falls         1.30            90

Hudson             1.60            80

Ellsworth           1.80            70

Prescott             2.00            30

Rock Elm           2.40            28

Stillwater           2.90            22

(a) Set up a scatter diagram.

(b) Assuming a linear relationship, use the least-squares method. This means to apply

the formulas for bo and b1 to find the regression coefficients bo and b1. Write the

predicted equation for this problem.

(c)  Interpret the meaning of the y-intercept bo and slope b1 by relating the interpretation

to Price and Sales.

(d) Predict the sales when the prices are \$1.50 and \$2.70, and \$3.50.