Question 42788
WIND SPEED =W……PLANE SPEED IN STILL AIR =P
SPEED IN TAIL WIND =P+W……….SPEED IN HEAD WIND =P-W………D=1000
TIME FOR TRAVEL IN TAIL WIND =1000/(P+W)=2…..OR……P+W=500……………..I
TIME FOR TRAVEL IN HEAD WIND =1000/(P-W)=2.5…..OR……P-W=400……………..II
EQN.I+EQN.II…….2P=900…..P=450
HENCE W =50
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LET RENT/DAY=D…….AND…..RATE PER MILE =M
CHARGE FOR 5 DAYS =5D…….CHARGE OR 150 MILES =150M….TOTAL = 5D+150M=180….OR….D+30M=36…………….I
CHARGE FOR 7 DAYS =7D…….CHARGE OR 320 MILES =320M….TOTAL = 7D+320M=274…………..…………….II
EQN.II-7*EQN.I……7D+320M-7D-210M=274-252=22……..110M=22………..M=0.2 $/MILE
D=36-30*0.2=36-6=30 $/DAY