Question

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

Hint:
If y varies directly with x then y = kx

Answer 2

In order to solve this problem, find the value of k first.

Answer 3

If y = 5 and x = 2.5, then
5 = 2.5k
5/2.5 = k
2 = k

Answer 4

To find the value of y when x = 10, use the formula, y = kx, except this time, substitute x = 10 and k = 2 into the formula:

y = kx
y = 2(10)
y = 20