Question:
To compute for the volume of the trough, use the formula:
Volume = L \u00D7 W \u00D7 H
$8636_w291_h20.png$
The information about 2.8 inches rise in slop is unnecessary because you are asked to find the volume of the trough, not that of the slop.
Be careful to be aware of, and discard, any irrelevant information given in test questions.