Question

Y ∝ x². When x=4, y=48. What does y equal when x is 6

Answer 1

y = 108

Explanation:

given y ∝ x² then the equation relating them is

y = kx² ← k is the constant of proportion

to find k use the condition when x = 4 , y = 48

48 = k × 4² = 16k ( divide both sides by 16 )

3 = k

y = 3x² ← equation of proportion

when x = 6 , then

y = 3 × 6² = 3 × 36 = 108

Answer 2

The answer must be 108.

The symbol for a proportion between two variables is given. If x=4 and y=48, it is obvious that there is a hidden factor "3". Similarly, when x=6, y=108 because 36.3=108.