Question

If y is 5 when x is 2.5 and y varies directly with x, find y when x is 10.


5
7.5
12.5
20

Answer 1

use y =kx

Answer 2

then you have 5 = 2.5K
which is 5/2.5 = k
so K = 2

Answer 3

y= 20 because y varies directly with x means y=kx, where k is a constant of the variation so
kx=10
y=(2)(10)
y=20

Answer 4

now when x = 10
then y = 2.10
y = 20