Determine whether y varies directly with x. If so, find the constant of variation k.

x: y:
4 6.4
7 11.2
10 16
13 20.8

Question

Determine whether y varies directly with x. If so, find the constant of variation k.

x:        y:
4         6.4
7         11.2
10       16
13       20.8

anonymous · Answer

I forgot how to do this. x1 y2 or something?

anonymous · Answer

When y varies directly with x the equation is y=kx. So you would plug in the x values in place of x and the y in place of y, then you solve for k by dividing both sides by the x value. In this case each time you divide you get 1.6 directly.

anonymous · Answer

*so it varies directly.

anonymous · Answer

So, 6.4 = (k)4?

anonymous · Answer

yes. and 
11.2=7(k)
16=10(k)
20.8=13k

anonymous · Answer

I see. Thanks. 

1.6 is the constant and I just have to do each set.

anonymous · Answer

yeah, sorry if that came across unclear.