Question

If y varies inversely as x and y=3 when x=5, find x when y=2.5

Answer 1

x = 6

Explanation:

given y varies inversely as x , then the equation relating them is

y =
`(k)/(x)` ← k is the constant of variation

to find k , substitute y = 3, x = 5 into the equation

3 =
`(k)/(5)` ( multiply both sides by 5 )

15 = k

y =
`(15)/(x)` ← equation of variation

when y = 2.5 , then

2.5 =
`(15)/(x)` ( multiply both sides by x )

x × 2.5 = 15 ( divide both sides by 2.5 )

x =
`(15)/(2.5)` = 6