The answer is 7.
The formula to find the surface area of a cylinder is
[tex]a =2 \pi {r}^{2} + 2\pi rh[/tex]
Plug in the givens:
[tex]615.44 = 2 \times 3.14 \times {7}^{2} + 2 \times 3.14 \times 7 \times h[/tex]
Eliminate the exponents:
[tex]615.44 = 2 \times 3.14 \times 49 + 2 \times 3.14 \times 7 \times h[/tex]
Multiply the numbers:
[tex]615.44 = 307.72 + 43.96h[/tex]
Subtract 307.72 from both sides:
[tex]43.96h = 307.72[/tex]
Divide both sides by 43.96:
[tex]h = 7[/tex]
