A large, spherical-shaped balloon is used by a car lot to advertise the current car loan interest rate. The surface area of the balloon is 254.47 ft². What is the length of the radius for this sphere?

Question

Round your answer to the nearest hundredth.

Answer 1

Hi Erica,

This is a nice straightforward problem if you know the following equation for the surface area of a sphere:

A = 4 π r²

The prompt gives us a surface area of A = 254.47 ft². All we have to do is plug this into our equation and solve for the radius, r. This looks like:

(254.47 ft²)=4 π r²

Dividing both sides by 4π to get r² by itself, we get:

20.25 ft² = r²

Finally, taking the square root of both sides of the equation:

√(20.25 ft²) = √(r²)

4.50 ft = r

And you're good to go :)