A fish tank measures 36 inches long, 24 inches wide, and 20 inches high. Approximately how many pounds of water does it hold?

A fish tank measures 36 inches long, 24 inches wide, and 20 inches high. Approximately how many pounds of water does it hold?

• A. 64.4 lbs
• B. 74.8 lbs
• C. 83.4 lbs
• D. 624 lbs

Answer: (D)

The main idea is to turn the tank’s interior into a weight by converting its volume into gallons, then using the weight of water per gallon. First find the volume in cubic inches: 36 × 24 × 20 = 17,280 in³. A gallon holds 231 in³, so the tank’s volume is 17,280 ÷ 231 ≈ 74.8 gallons. Water weighs about 8.34 pounds per gallon, so the total weight is 74.8 × 8.34 ≈ 624 pounds. Therefore, the tank holds about 624 pounds of water.

The main idea is to turn the tank’s interior into a weight by converting its volume into gallons, then using the weight of water per gallon.

First find the volume in cubic inches: 36 × 24 × 20 = 17,280 in³. A gallon holds 231 in³, so the tank’s volume is 17,280 ÷ 231 ≈ 74.8 gallons. Water weighs about 8.34 pounds per gallon, so the total weight is 74.8 × 8.34 ≈ 624 pounds. Therefore, the tank holds about 624 pounds of water.