Question

The exterior surface of a farm silo needs to be painted. If one gallon of paint covers 224 square feet, what is the minimum number of gallons needed to paint the silo? Keep in mind that the bottom of the silo is not painted. Use π = 3.14A. 18 gallonsB. 19 gallonsC. 21 gallonsD. 23 gallons

Answer 1

step 1

Find out the surface area of the figure

The surface area of the cylinder (without the base and the top)

`SA=2\pi rh`

where

r=12 ft

h=50 ft

pi=3.14

substitute

SA=2(3.14)(12)(50)

SA=3,768 ft2

step 2

Find out the surface area of the hemisphere

SA=2pir^2 ------> surface area of hemisphere

we have

pi=3.14

r=12 ft

substitute

SA=2(3.14)(12^2)

SA=904.32 ft2

step 3

the total surface e area is

3,768+904.32=4,672.32 ft2

step 4

Find out the number of gallons

we have that

1 gallon -------> 224 ft2

so

applying proportion

4,672.32/224=20.85 gal

therefore

the answer is 21 gal option C