Question

If x varies inversely as y, and x = 11 when y = 15, find x when y = 3.

a:11/5

b:33/15

c:55

Answer 1

C

Explanation:

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

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

To find k use the given condition x = 11 when y = 15

k = xy = 11 × 15 = 165 , hence

x =
`(165)/(y)` ← inverse variation equation

when y = 3, then

x =
`(165)/(3)` - 55 → C

Answer 2

55

Explanation:

The equation of inverse variation is

y = k/x,

where k is a constant.

We can use the given x- and y-coordinates to find k.

y = k/x

15 = k/11

k = 165

The inverse variation equation for this problem is

y = 165/x

For y = 3,

3 = 165/x

3x = 165

x = 55