A thief seeing a policeman at a distance of 150 metres starts running at 10 kmph and the policeman gives immediate chase at 12 kmph. When the thief is overtaken the thief has traveled a distance of:
A. 750 m
B. 900 m
C. 800 m
D. 1 km
Answer: Option A
Solution(By Examveda Team)
P__150m___T______x m (Let)_______Q. Let Policeman caught thief at a distance (x + 150)m. And Thief has traveled x m. Speed of Policeman$$\eqalign{ & = 12\,\,{\text{kmph}} \cr & = \frac{{12 \times 5}}{{18}} \cr & = \frac{{60}}{{18}}\,\,{\text{m/sec}} \cr} $$ Speed of thief
$$\eqalign{ & = 10\,\,{\text{km}} \cr & = \frac{{10 \times 5}}{{18}} \cr & = \frac{{50}}{{18}}\,\,{\text{m/sec}} \cr} $$ In this case time is constant means Policeman covered (x + 150)m in same time thief covered x m. Thus, $$\eqalign{ & \frac{{{\text{Speed of the thief}}}}{{{\text{Speed of Policeman}}}} = \frac{x}{{150 + x}} \cr & \Rightarrow \frac{{50}}{{60}} = \frac{x}{{150 + x}} \cr & \Rightarrow 7500 + 50x = 60x \cr & \Rightarrow 10x = 7500 \cr & \Rightarrow x = 750\,{\text{m}} \cr} $$ So, Thief has traveled 750 m before the caught.
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Comments ( 2 )
Related Questions on Speed Time and Distance
A. 48 min.
B. 60 min.
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D. 62 min.
E. 66 min.
A. 262.4 km
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let thief distance cover =x meters
police=x+150
so x/10=x+150/12=750 meters
why is the time constant?