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MATHEMATICS FOR AIR CREW TRAINEES 13-14

 (10) An airplane travels 400 miles in 2 hours. Set up a proportion and determine how far the airplane will travel in 14 hours.
                                     2,800 miles. Answer.

 (11) If 1/10 inch on a map represents 49 miles, how many miles are represented by 3 inches on the map?

 (12) If a boat drifts down stream 40 miles in 12 hours, how far will it drift in 15 hours?
                                        50 miles. Answer.

 (13) On June 12, 1939, a pilot flew a glider plane across Lake Michigan a total distance of 92 miles in 52 minutes. He cut loose from the tow plane at 13,000 feet and descended only 5,000 feet in crossing. At the same rate of descent, how much farther could he have glided? How many more minutes would he have been in the air?

 (14) A roadbed rises 3 1/3 feet in a horizontal distance of 300 feet. How many feet will the roadbed rise in 720 feet?
                                            8 ft. Answer.

 (15) If 16 gallons of gas will drive a car 288 miles, at the same rate of using gas how many gallons will it take a driver the same car from Chicago to Memphis, a distance of 564 miles?

 h. Conversion exercises.-Obtain conversion factors required in the following examples from the appendix.
  (1) Change 210 miles per hour to knots.
  (2) How many feet per second are 32 miles per hour?
                                     46.9 ft/sec. Answer.
  (3) Express 58 centimeters in inches.
  (4) Convert the following to nautical miles:
  (a) 230 statute miles.   199.7 nautical miles. Answer.
  (b) 34.5 statute miles.   29.9 nautical miles. Answer.
  (c) 4,025 statute miles.3,495.3 nautical miles. Answer.

 (5) A tank containing 125 U.S. gallons of gas would contain how many British gallons?

 (6) How many U.S. gallons are there in 78.5 British gallons?             
                                   94.2 U.S. gal. Answer.
 
 14. Positive and negative numbers.-There are many quantities which by their contrary or opposite nature are best described as negative quantities in contrast to positive quantities. For example, temperatures above 0° Fahrenheit are considered as positive, whereas those below 0° are considered as negative. As a consequence it becomes necessary to consider negative and positive numbers and how to deal with them. 

  a. A negative number is indicated by prefixing a minus sign (-) in front of the number. Thus -5, -7.04, -90.003 are all negative numbers.

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