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                MATHEMATICS FOR AIR CREW TRAINEES                     9 

 (2) Example: Express 19/4 as a decimal.
     Solution: 4.7500 / 4/19.000000 Therefore 19/4 = 4.75        Answer.                                     

 b. To express any fraction as a percent, first change the fraction to a decimal fraction as in a above, then change the decimal fraction to a percent as in paragraph 8. 

 Example: Express 7/12 as a percent.
 Solution: .58333 . . . / 12/7.000000 Therefore 7/12 = .583333 . . .
 (The series of dots indicated that the decimal fraction may be con-tinued indefinitely by adding 3's.)
 Therefore  7/12 = .58333 . . . = 58.3 percent                     Answer.

 c. Percent problems. --- The following examples illustrate the con-verse (reverse) of those given in paragraph 8. 
 (1) Example: If 18 airplanes out of a squadron of 27 airplanes are available for combat, what percent of the squadron aircraft is avail-able for combat? What percent is not available for combat? 
     Solution: 18/27 = .6666 . . . = 67 percent available for combat 
                                                                   Answer. 
               100 percent - 67 percent = 33 percent not available for 
               combat 
or             9/27 = .333 . . . = 33 percent                      Answer. 
 (2) Example: At a pressure altitude of 20,000 feet with the air temperature at 10° below zero, the calibrated air speed in 200 knots, and the true air speed is 282 knots. What is the percent increase in the air speeds? Compare the true air speed with the calibrated air speed.
     Solution: 282 knots - 200 knots = 82 knots.
               82 knots/200 knots = .41 = 41 percent increase         
                                                                  Answer.
              282 knots/200 knots = 1.41 = 141 percent. Therefore the true 
              air speed is 141 percent of the calibrated
              air speed.                                          Answer.                           
 d. Exercises. 
 (1) The top speed of an aircraft at 8,000 feet is 304 mph. At 12,000 feet the top speed is 352 mph. What is the percent of increase in speed?

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