Question

Y is directly proportional to x when y=30, x=6

a) work out an equation connecting y and x
b) work out the value y when x=12

Answer 1

a) y = 5x

b) y = 60

Explanation:

Since, y is directly proportional to x when y=30, x=6

`\therefore \: y \: \alpha \: \: x \\ \therefore \: y = kx ...(1) \\ plug \: y = 30 \: and \: x = 6 \: in \: eq \: (1)\\ 30 = k * 6 \\ k = (30)/(6) \\ k = 5 \\ plug \: k = 5 \: in \: (1) \\ y = 5x....(2) \: (required \: equation) \\ plug \: x = 12 \: in \: eq \: (2) \\ y = 5 * 12 \\ \huge \red{ \boxed{y = 60}}`