Find an equation of variation in which y varies direct as x and y=0.8 and x=0.5. Then find the value of y when x=20.

Question

An equation of variation is y=

 

The value of y is __ when x=20

Answer 1

Hi Bob,

 

y ∝ x

so y=kx where k is constant

 

y= 0.8, x= 0.5

 

substituting this values in eqn, y = kx, we get

 

0.8 = k*0.5

 k = 0.8/0.5 = 8/5

 

now eqn is y = 8/5 * x

 

x= 20 so y = 8/5 * 20 = 32.