Question

If the radius of a sphere is doubled, the percent increase in volume is

• A. 100
• B. 200
• C. 400
• D. 700
• E. 800

Answer 1

Answer: (D)

700

Let the radius be $r$
Volume of sphere is $V1=\frac{4}{3}\times \pi r^3=v$
Now the radius is doubled, then the new volume is $V2=\frac{4}{3}\times \pi r^3\times 8=8v$
The percent increase in volume is $\frac{(V2-V1)}{V1}\times 100=\frac{(8v-v)}{v}\times 100=700$ percent.