In a flight of 600 km, an aircraft was slowed down due to bad weather. Its average speed for the trip was reduced by 200 km/hr and the time of flight increased by 30 minutes. The duration of the flight is:
A. 1 hour
B. 2 hours
C. 3 hours
D. 4 hours
Answer: Option A
Solution(By Examveda Team)
$$\eqalign{ & {\text{Let}}\,{\text{the}}\,{\text{duration}}\,{\text{of}}\,{\text{the}}\,{\text{flight}}\,{\text{be}}\,x\,{\text{hours}} \cr & {\text{Then}},\frac{{600}}{x} - \frac{{600}}{{x + \left( {1/2} \right)}} = 200 \cr & \Rightarrow \frac{{600}}{x} - \frac{{1200}}{{2x + 1}} = 200 \cr & \Rightarrow x\left( {2x + 1} \right) = 3 \cr & \Rightarrow 2{x^2} + x - 3 = 0 \cr & \Rightarrow (2x + 3)(x - 1) = 0 \cr & \Rightarrow x = 1\,\text{hour} \cr} $$Join The Discussion
Comments ( 3 )
Related Questions on Speed Time and Distance
A. 48 min.
B. 60 min.
C. 42 min.
D. 62 min.
E. 66 min.
A. 262.4 km
B. 260 km
C. 283.33 km
D. 275 km
E. None of these
A. 4 hours
B. 4 hours 30 min.
C. 4 hours 45 min.
D. 5 hours
The answer is 1.5 hour please check your answer
Examveda
Let,the speed of flight = x km/hr
So,
600/(x-200) - 600/x = 1/2
=> (x-x+200)/x(x-200) = 1/1200
=> 1/(x^2-200x) = 1/1200*200
=> x^2 - 200x - 400*600 = 0
=> (x+400)(x-600) = 0
=> x = 600 km/hr
Duration of flight = 600km/600km/hr = 1hr
Let,the speed of flight = x km/hr
So,
600/(x-200) - 600/x = 1/2
=> (x-x+200)/x(x-200) = 1/1200
=> 1/(x^2-200x) = 1/1200*200
=> x^2 - 200x - 400*600 = 0
=> (x+400)(x-600) = 0
=> x = 600 km/hr
Duration of flight = 600km/600km/hr = 1hr