Question

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

$8$

$12$

$20$

$24$

$48$

Difficulty rating: 930

The $4$ gallons account for the change from $\dfrac13$ full to $\dfrac12$ full, which is $\dfrac12 - \dfrac13 = \dfrac16$ of the capacity.

If $\dfrac16$ of the capacity is $4$ gallons, the full capacity is $4 \times 6 = 24$ gallons.

Thus, the correct answer is D .