Solve using table of values

Question

The Winter Sports Shoppe has seen a steady increase in the sales of snowboards over the last three years . They sold 120 snowboards the first year, 280 the second year, and 440 this year. If the pattern continues, how many snowboards might they sell in the sixth year ?
* I know the answer just not sure how to set up the table*

Answer 1

just make a table with two columns
Each column will have a row for the year # and its associated sales

Answer 2

Mark years with x and sold snowboards with y.

x1 = 1 , y1 = 120

x2 = 2 , y2 = 280

x3 = 3 , y = 440

y2 - y1 = 280 - 120 = 160

y3 - y2 = 440 - 280 = 160

Difference is constant.

This mean, equation is linear , y = m x + c

m is the slope of the line.

m = ( y2 - y1 ) / ( x2 -x1 )

In this case:

m = ( 280 - 120 ) / ( 2 -1 )

m = 160 / 1 = 160

Replace this value in equation:

y = m x + c

y = 160 x + c

Put x = 1 , y = 120 in equation y = 160 x + c

120 = 160 ∙ 1 + c

120 = 160 + c

120 - 160 = c

c = - 40

Your function is:

y = 160 x - 40

In the sixth year x = 6

y = 160 x - 40

y = 160 ∙ 6 - 40

y = 960 - 40 = 920

Answer 3

Of course, you can also create a table.

The difference is a constant = 160 and you just put in the table:

year is the previous year + 1

sales = sales of in previes year + 160

The table looks like this.

1 | 120

2 | 280

3 | 440

4 | 600

5 | 760

6 | 920