Y varies directly as x, and y=4 when x=8. Find y when x=10

Answer 1

Since y varies directly as x, y = kx, for some constant, k.

 

y = 4 when x = 8    So, 4 = 8k

 

                                   k = 1/2

 

y = (1/2)x

 

Therefore, when x = 10, y = (1/2)(10) = 5