Average rate of evaporation

[chieftang]

The water from a swimming pool will evaporate at a rate of 12 gallons per hour in the sun, and at a rate of 4 gallons per hour in the shade. In August, the amount of water lost to evaporation in the sun was the same as the amount of water lost to evaporation in the shade.

What was the average rate of evaporation in August?

(A) 3 gallons per hour
(B) 6 gallons per hour
(C) 8 gallons per hour
(D) 10 gallons per hour
(E) 12 gallons per hour

OA: [spoiler]B, See rijul007's explanation[/spoiler]

[rijul007]

The water from a swimming pool will evaporate at a rate of 12 gallons per hour in the sun, and at a rate of 4 gallons per hour in the shade. In August, the amount of water lost to evaporation in the sun was the same as the amount of water lost to evaporation in the shade.

What was the average rate of evaporation in August?

(A) 3 gallons per hour
(B) 6 gallons per hour
(C) 8 gallons per hour
(D) 10 gallons per hour
(E) 12 gallons per hour

OA: To come

No of hrs in the sun = x
No of hrs in the shade = y

Amount of water lost in the sun = 12x
Amount of water lost in the shade = 4y

12x = 4y
y = 3x
Total no of hours = x + y = 3x + x = 4x
Total amount lost = 12x + 4y = 12x + 12x = 24x

Avrg rate = 24x/4x = 6

Option B