Question

If y varies inversely as x and y is 2.5 when x is 6, what is y when x is 4? a. 3.75 b. 1.67 c. 0.1 d. 7.5 Please select the best answer from the choices provided

Answer 1

Inverse proportion is given in the form

`y= (k)/(x)`

We need to work out the constant, k, by substituting x = 6 and y = 2.5

`2.5= (k)/(6)`

`k=2.5*6`

`k=15`

The value of y when x = 4

`y = (15)/(x)`

`y= (15)/(4)`

`y=3.75`

Answer 2

Because y varies inversely as x, therefore

`y= (k)/(x)`
where k = constant.

When x = 6, y = 2.5. Ther efore

`(k)/(6) = 2.5`
Cross multiply.
k = 6 x 2.5 = 15

The equation is

`y = (15)/(x)`

When x = 4, obtain

`y = (15)/(4)= 3.75`

Answer: a. 3.75