The following instructions are for entering data in Microsoft Excel, ClarisWorks, or AppleWorks. The actual spreadsheet is at the bottom of this page as well as the data table.

Enter the all the data from the Activity and Calories Chart in the 125 lb and 150 lb columns in column A and column B on your spreadsheet. Place 125 and 150 at the top of each column. (Do not type lb behind 125 and 150)

According to the chart a person who weighs 125 pounds burns 95 calories while gardening for 10 minutes. This can be translated into the point (125, 95). A person who weighs 150 pounds burns 115 calories while gardening for 10 minutes translates into the point (150,115). A person who weighs 115 pounds burns how many calories (y) while gardening for 10 minutes?

Write an equation given the two points (125, 95) and (150,115).

First label a column "slope" then recall the slope formula. m = (y₂-y₁)/(x₂-x₁)

According to these instructions points (125, 95) are in (A1, A2) and (150,115) are in (B1, B2).

Substituting cell numbers in the formula yields the following formula to be placed in C2: =(B2-A2)/($B$1-$A$1).

This formula yields 0.8 in C2. The $ signs keep the numbers in cells B1 and A1 constant when we fill in the columns.

Place the curser in C2 and pull down on the small square in the bottom right corner to fill in the remainder of column C. (If using AppleWorks or ClarisWorks go to Calculate and Fill Down.)

Create a column that will compute the 175 lb column. This step is to help you check your formulas by letting you compare your results with the results in the Activity and Calories Chart.

Place 175 in D1.

Use the slope and one of the points to find how many calories will be burned doing aerobics for 10 minutes. Solve the formula for y₁. The slope is 0.8 (C2) and the point (x₁, y₁) is (125, 95) in cells (A1, A2).

If (x₂, y₂) is the point (175, y₂) in cells (D1, D2) find y₂ which is D2.

Solve the equation m = (y₂-y₁)/(x₂-x₁) for y₂. This will translate into y₂ = m(x₂-x₁) + y₁

Or D2 = C2($D$1-$A$1) + A2. ( An asterisk, *, must be used because the spreadsheet does not recognize implied multiplication.) Enter the formula = C2*($D$1-$A$1) + A2 in D2 and the value 135 should appear. For Excel highlight D2 and pull down the corner of the cell to the bottom of the rows. (For AppleWorks go to Calculate and Fill Down.) The resulting numbers should be very close to or the same as the numbers in the 175 pound column on the original table.

To find the number of calories that are burned by a person who weighs 240 pounds, change 175 in D1 to 240.

Notice that all the numbers in D column change. Students can place any number in D1 (even their own weight) to represent a list of calories burned in 10 minutes.

The table below gives the caloric expenditure after 10 minutes of activity for various body weights. This data was obtained from Reebok Instructor News, Volume 4, Number 2, 1991.

http://kirtland.cc.mi.us/~balbachl/calorie.htm

Spreadsheet Example described above.