VARIATION H5

x is inversely proportional to y. x=18 while y=5. Find y when x is 15.

 

Solution

 

x ⍺ k

      y

 

x = k

      y

 

18 = k

        5

 

k = 18 x 5

 

k = 90

 

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

 

k = 90, y= ?, x = 15.

 

x = k

     y

 

15 = 90

        y

 

y x 15 = 90  x  y   (multiply by y on both sides)

              y

 

 

15y = 90

15      15

 

Hence y = 6  .

 

 

TRY THIS…………….

 

 

x is inversely proportional to y. x=80 while y=4. Find y when x is 10.