Determine whether y varies directly with x. if so, find the constant of variation k.. x: y: . 4 a 6.4 and 7 b.11.2 and 10 c.16 and 13 d.20 and 8

Direct Variation:

y = kx

   x       y
   4     6.4
   7   11.2
10   16
13    20.8

6.4 = k*4
k = 6.4 / 4 
k = 1.60

11.2 = k * 7
k = 11.2 / 7
k = 1.60

16 = k * 10
k = 16/10
k = 1.60

20.8 = k * 13
k = 20.8/13
k = 1.60

In this problem y varies directly with x. The constant of variation, k, is equal to 1.60