Question

If y=1/2 when x=5 find y when x=7 given that y varies directly with x. Y=?

Answer 1

For direct variation, an increase or decrease in one variable leads to a corresponding increase or decrease in another variable. Given that y varies with x, we would introduce a constant of proportionality, k. it becomes

y = kx

Given that y = 1/2 when x = 5, it means that

1/2 = 5k

k = 0.5/5 = 0.1

The equation becomes

y = 0.1x

When x = 7,

y = 0.1 * 7 = 0.7