Answer:
R = 30
Explanation:
Given y is directly proportional to R² then the equation relating them is
y = kR² ← k is the constant of proportion
To find k use the condition when R = 4, y = 24, then
24 = k × 4² = 16k ( divide both sides by 16 )
1.5 = k
y = 1.5R² ← equation of proportion
When y = 1350 , then
1350 = 1.5R² ( divide both sides by 1.5 )
900 = R² ( take the square root of both sides )
= R , that is
R = 30