using a variation model to find the rent space

Question

the cost of renting office space in a downtown office building varies directly with the size of the office. A 600 square-foot office rents for $2550 per month. Use a variation model to find the rent on a 690 square-foot office

Answer 1

Direct variation:

y = kx

2550 = 600k           divide both sides by 600

4.25 = k                  multiply both sides by 690

 

y = 4.25x

y = 4.25(690)

y = 2932.50

 

Or by proportion:

 

600 : 2550 :: 690 : x       product means/extremes

600x = 2550(690)
600x = 175950

x = 2932.50