Question

If z is inversely proportional to x and z = 5 when x = 7, find the value of x when z = 70

Answer 1

x =
`(1)/(2)`

Explanation:

Given that z is inversely proportional to x then the equation relating them is

z =
`(k)/(x)` ← k is the constant of proportion

To find k use the condition z = 5 when x = 7 , then

5 =
`(k)/(7)` ( multiply both sides by 7 )

35 = k

z =
`(35)/(x)` ← equation of proportion

When z = 70 , then

70 =
`(35)/(x)` ( multiply both sides by x )

70x = 35 ( divide both sides by 70 )

x =
`(35)/(70)` =
`(1)/(2)`