Question

If m varies directly with t, and m = 4 when t = 12, what is the value of t when m = 12?

O4
O20
O24
O36

Answer 1

t = 36

Explanation:

given that m varies directly with t then the equation relating them is

m = kt ← k is the constant of variation

to find k use the condition m = 4 when t = 12 , then

4 = 12k ( divide both sides by 12 )

`(4)/(12)` = k , that is

k =
`(1)/(3)`

m =
`(1)/(3)` t ← equation of variation

when m = 12 , then

12 =
`(1)/(3)` t ( multiply both sides by 3 to clear the fraction )

36 = t