Question 261344
What is the radius of a tennis ball with a surface area of 28 in.²?
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A tennis ball is a sphere.  The formula for the surface area of a sphere is

{{{A = 4pi*r^2}}}

We substitute 28 for A and solve for r

{{{28 = 4pi*r^2}}}

Divide both sides by {{{4pi}}}

{{{28/(4pi) = r^2}}}

{{{7/(pi) = r^2}}}

Take the square root of both sides:

{{{sqrt(7/pi)= r}}}

Punch that out on a calculator and you
get 1.49270533 inches, which rounds to 
1.5 inches, choice A.

Edwin</pre>