Yuri O. answered • 02/12/21

16 years online, 464 former SAT problems drilled down

LSA_{cylinder} = 2πrh

LSA - lateral surface area

r - radius of the base of the the cylinder

h - altitude

r = 12 (ft)

h = 50 (ft)

LSA_{cylinder} = 2π•12•50 = 3,769.91 (ft^{2})

LSA_{hemisphere} = 2πr^{2}

LSA - lateral surface area

r - radius of the base

LSA_{hemisphere} = 2π•12^{2} = 904.78 (ft^{2})

LSA_{observatory} = LSA_{cylinder} + LSA_{hemisphere} = 3,769.91 + 904.78 = 4,674.69 (ft^{2})

Calculating the number of gallons of paint needed to put 2 layers of paint:

P = 2 • LSA_{observatory}/400 = 2 • 4,674.69/400 = 23.37 (gallons)

**P = 24** (gallons) ← needed to buy

Maddie U.

Thank you!02/13/21