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

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

$0.81$

Answer 2

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