# Change in volume and surface area

• Apr 8th 2010, 02:05 PM
elexis10
Change in volume and surface area
Need some help, been stuck

A spherical balloon has a radius of 5 in.

Estimate the change in volume if the radius increases by 0.3 in. Give your answer correct to one decimal place.

Estimate the change in surface area if the radius increases by 0.3 in. Give your answer correct to one decimal place.

Thank you
• Apr 8th 2010, 02:35 PM
sigma1
using the formula for finding the volume of a sphere $\displaystyle v= \frac {4}{3} pie R^3$

find the volume of the sphere at r=5
then find the volume of the sphere at r=5+.3=5.3

subtract the answers to get the increase in the volume.

do the similar operation for the surface are but using the surface area formula of $\displaystyle S=4pie R^2$

hope that helps.
• Apr 8th 2010, 04:50 PM
elexis10
this is what i had done first and i got 100.0 and 38.8 but these answers were incorrect so i thought i had made an error? i will keep on trying, thank you for your time and your help though