In a 800 metre race, A defeated B by 15 seconds. If A's speed was 8 km/hr, the speed of B was -
A. $$\frac{{16}}{{27}}{\text{ km}}/{\text{hr}}$$
B. $$\frac{{27}}{{16}}{\text{ km}}/{\text{hr}}$$
C. $$7\frac{{17}}{{25}}{\text{ km}}/{\text{hr}}$$
D. $$8\frac{{17}}{{25}}{\text{ km}}/{\text{hr}}$$
Answer: Option C
Solution (By Examveda Team)
A's speed= 8 km/hr
= $$\left( {8 \times \frac{5}{{18}}} \right)$$ m/sec
= $$\frac{20}{9}$$ m/sec
Time taken by A to cover 800 m
= $$\left( {800 \times \frac{9}{{20}}} \right)$$ sec
= 360 sec
Time taken by B to cover 800 m
= (360 + 15) sec
= 375 sec
∴ Speed of B :
= $$\frac{800}{375}$$ m/sec
= $$\left( {\frac{{800}}{{375}} \times \frac{{18}}{5}} \right)$$ km/hr
= $$\frac{192}{25}$$ km/hr
= $$7\frac{17}{25}$$ km/hr
This Question Belongs to Arithmetic Ability >> Races And Games
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