Question

Suppose that y varies directly with x and y = 10 when x = 20. What is y when x = 15?

Answer 1

Given that,

y varies directly with x and y = 10 when x = 20.

To find,

The value of y when x = 15.

Solution,

`y\propto x\\\\y=kx`

Put x = 20 and y = 10

`k=(y)/(x)\\\\k=(10)/(20)\\\\=(1)/(2)`

Put k = 1/2 and x = 15 to find the value of y.

`y=(1)/(2)* 15\\\\=7.5`

So, the value of y is 7.5