Answer:
C = 97.20
Step-by-step explanation:
Given that C varies as r² then the equation relating them is
C = kr² ← k is the constant of variation
To find k use the condition C = 202.80 when r = 2.6
k = [tex]\frac{C}{r^{2} }[/tex] = [tex]\frac{202.8}{2.6^{2} }[/tex] = 30
C = 30r² ← equation of variation
When r = 1.8, then
C = 30 × 1.8² = 97.20
