Question

Suppose r varies directly with t and that r = 25 when t=25 . What is the value of r when t = 7?

Answer 1

`r=7`

Explanation:

`"we are given "rpropt`

`"to convert to an equation multiply by k the constant"`
`"of variation"`

`r=kt`

`"to find k use the given condition"`

`r=25" when "t=25`

`r=ktrArrk=r/t=25/25=1`

`"equation is "r=t`

`"thus when t = 7 "r=7`