Answer:
E = 56
Step-by-step explanation:
Given that E varies directly with [tex]\sqrt{C}[/tex] then the equation relating them is
E = k[tex]\sqrt{C}[/tex] ← k is the constant of variation
To find k use the condition E = 40 when C = 25
k = [tex]\frac{E}{\sqrt{C} }[/tex] = [tex]\frac{40}{\sqrt{25} }[/tex] = [tex]\frac{40}{5}[/tex] = 8, thus
E = 8[tex]\sqrt{C}[/tex] ← equation of variation
When C = 49, then
E = 8 × [tex]\sqrt{49}[/tex] = 8 × 7 = 56
