Question

Suppose that y varies directly with x, and y=4 when x=20. (a) Write a direct variation equation that relates and y Equation: (b) Find y when x=9. y=​

Answer 1

(a) Since y varies directly with x, hence, y = kx, where k is a constant.

(b) When x = 20, y = 4

20k = 4

∴ k = 0.2

∴ When x = 9,

y = 9(0.2)

y = 1.8