Question

Find the value of y for a given value of x, if y varies directly with x. If y = 2.52 when x = 8.4, what is y when x = 2.7?  (1 point) 9 –9 0.81 –0.81

Answer 1

8.4/2.52 = 2.7/y
cross multiply:
8.4y = 6.80
y = 6.80/8.4 = choice (D)

Answer 2

we know that

A relationship between two variables, x, and y, represent a direct variation if it can be expressed in the form
`(y/x)=k\ or\ y=kx`

in this problem we have

`y = 2.52\ when\ x = 8.4`

so

Find the value of the constant k

`(y/x)=k`

substitute

`k=(2.52/8.4)`

`k=0.3`

the equation is equal to

`y=0.3x`

Find the value of y when
`x=2.7`

substitute the value of x in the equation

`y=0.3*2.7`

`y=0.81`

therefore

the answer is

`0.81`