Question

(C) c varies directly as a and inversely as b. If c= 15 when a = 18 and b = 40, find c when a = 36, and b = 25. = с​

Answer 1

c = 48

Explanation:

Given c varies directly as a and inversely as b then the equation relating them is

c =
`(ka)/(b)` ← k is the constant of variation

To find k use the condition c = 15 when a = 18 and b = 40 , then

15 =
`(18k)/(40)` ( multiply both sides by 40 )

600 = 18k ( divide both sides by 18 )

`(600)/(18)` = k

`(100)/(3)` = k

c =
`(100a)/(3b)` ← equation of variation

When a = 36 and b = 25 , then

c =
`(100(36))/(3(25))` =
`(3600)/(75)` = 48