Question

After 4,000 gallons of water were added to a large water tank that was already filled to 3/4 of its capacity, the tank was then at 4/5 of its capacity. How many gallons of water does the tank hold when filled to capacity?(A) 5,000(B) 6,200(C) 20,000(D) 40,000(E) 80,000

Answer 1

Answer: The correct option is

(E) 80,000.

Step-by-step explanation: Given that after adding 4,000 gallons of water to a large tank that was already filled to
`(3)/(4)` of its capacity, the tank was then at
`\drac{4}{5}` of its capacity.

We are to find the number of gallons of water that the tank hold when filled to capacity.

Let the tank can hold x gallons of water when filled to capacity.

Then, according to the given information, we have

`(3)/(4)x+4000=(4)/(5)x\\\\\\\Rightarrow (4)/(5)x-(3)/(4)x=4000\\\\\\\Rightarrow (16-15)/(20)x=4000\\\\\Rightarrow x=4000*20\\\\\Rightarrow x=80000.`

Thus, the required capacity of the tank is 80,000 gallons of water.

Option (E) is CORRECT.