A man goes to a place on bicycle at speed of 16 km/hr and comes back at lower speed. If the average speed is 6.4 km/hr in total, then the return speed (in km/hr) is :
A. 10 km/hr
B. 8 km/hr
C. 6 km/hr
D. 4 km/hr
Answer: Option D
Solution(By Examveda Team)
$$\eqalign{ & {\text{Average speed :}} \cr & {\text{ = }}\frac{{2xy}}{{x + y}} \cr & = \frac{{2 \times 16 \times y}}{{16 + y}} \cr & \Rightarrow 6.4 = \frac{{32y}}{{16 + y}} \cr & \Rightarrow 102.4 + 6.4 = 32y \cr & \Rightarrow 102.4 = 25.6y \cr & \Rightarrow y = \frac{{102.4}}{{25.6}} \cr & \Rightarrow y = 4{\text{ km/hr}} \cr} $$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
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