The model helicopter would burn 10.5 ounces of fuel in 7 1/2 minutes. You would first multiply 1.4 (1 2/5 ounces of fuel) by 7 minutes to get 9.8 ounces of fuel. Then, divide 1.4 by 2 to account for the thirty seconds of the flight ( thirty seconds is half of a minute, or 1/2) to get 0.7, add 0.7 by 9.8, and get 10.5 ounces of fuel in the process.
