Question

Y is directly proportional to X^2
If y = 45 when x = 3 find
y when x = 5

Answer 1

Y = 125

Explanation:

Y is directly proportional to X^2

Mathematically,

Y ∝ X²

Y = kX²

Where k = Constant of Proportionality

Step 1

If y = 45 when x = 3

We solve for k

Y = kX²

k = Y/X²

k = 45/3²

k = 45/9

k = 5

Step 2

find y when x = 5

Y = kX²

k = 5, X = 5

Hence,

Y = 5 × 5²

Y = 125