When four gallson are added to a tank that is one-third full, the tank is then one-half full. what is the capacity of the tank in gallons?

24 gallons

Step-by-step explanation:

To answer this question let's call "a" the capacity of the tank in gallons.

Initially it is one third of its capacity, but when 4 gallons are added, it is half full.

This statement can be written as an equation in the following way:

(1)

This equation represents the given conditions, therefore solving it we can clear "a" the capacity of the tank in gallons

Solving the equation we have:

Therefore the capacity of the tank is 24 gallons.

We can check this result by verifying if it meets the given conditions. The half of 24 is 12. Therefore, if we divide 24 at 3 and then add 4, we should get half the capacity of the tank, that is, 12 gallons.

12 is half the capacity of the tank, then equation (1) is met and the result is checked

step-by-step explanation:

12: 00 p.m. to 7: 00 p.m. is a total of 7 hours.

4: 00 p.m. to 7: 00 p.m. is a total of 3 hours.

this means that from 4: 00 p.m to 7: 00 p.m. this represents 3/7 of what was lost from 12: 00 p.m. to 7: 00 p.m.

after knowing this, after doing 11,600 - 6,800 = 4,800

4,800 represents 3/7 of what was lost for 7 hours.

we then divide 4,800 by 3 which gets 1,600.

because we know that 1,600 represents 1/7 of how much water was lost, we just have to multiply by 7, which gets 11,200.   after adding 11,200 to how much water was left at 7: 00 p.m. which was 6,800. 11,200 + 6,800 = 18,000

this means that the pool originally had 18,000 gallons in the pool.

you can also check your work by doing 18,000 - 4(1600), which becomes           1800 - 6400 which gets you 11,600.