Application of Quadratic Equations

Question

The cost of hiring a chainsaw is proportional to the square of the number of hours for which the chainsaw is hired. If it costs $32.50 to hire the chainsaw for 3 hours, find, to the nearest half hour, the length of time for which the chainsaw was hired if the cost of hire was $60.

Answer 1

You asked this a while ago, but for the record:

 

The ratio of the costs is $60 / $32.50  which is approx  1.846 .

Since the cost goes as the square of the time, the ratio of the

times must be the square-root of that, or about   1.359 .

So the hours of the $60 rental is  1.359 times the hours of the $32.50 rental.

  =  1.359 * 3 hours  = 4.076,

or very close to 4 hours.