Answer:
c = 31.5
Step-by-step explanation:
Given c varies directly as [tex]\sqrt{d}[/tex] then the equation relating them is
c = k[tex]\sqrt{d}[/tex] ← k is the constant of variation
To find k use the condition c = 14 when d = 64, then
14 = k ×[tex]\sqrt{64}[/tex] = 8k ( divide both sides by 8 )
1.75 = k
c = 1.75[tex]\sqrt{d}[/tex] ← equation of variation
When d = 324 , then
c = 1.75 × [tex]\sqrt{324}[/tex] = 1.75 × 18 = 31.5