Complete in Metric Conversions:

A drainage system for a 40 acre field is designed to remove 3/8 inch of standing water from the entire field in 24 hours. What flow rate (gpm) must the drainage system achieve to meet the design specification? (283 gpm)

Why are they calling this "metric" conversions? Acres, inches and gallons are not metric units.

Convert the number of acre-inches to gallons, and divide by 1440 minutes.

This may help:
http://www.bae.ncsu.edu/programs/extension/manure/awm/program/barker/a&pmp&c/conversion.htm