VARIATION 1A

x is directly proportional to y. x=32 while y=4. Find y when x is 720.

Solution

x ⍺ y

x = ky

32 = k x 4

32 = 4k    [dividing by 4 both sides]

4      4

k = 8

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

k = 8, y= ? x = 720.

x = ky

720 = 8 x y

720 = 8y

8       8

y = 90.

TRY THIS…………….

x is directly proportional to y. x=40 while y=4. Find y when x is 470.