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Two trains, Calcutta Mail and Bombay Mail, start at the same time from stations Kolkata and Mumbai respectively towards each other.After passing each other, they take 12 hours and 3 hours to reach Mumbai and Kolkata respectively. If the Calcutta mail is moving with the speed of 48 km/h , the speed of the Bombay mail is

(a)24 km/h  

(b)22 km/h

(c)21 km/h

(d)96 km/h
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I have an intuitive answer for this question. By the given facts, Calcutta mail takes 12 hrs whereas Mumbai mail takes 3 hrs after they cross each other. It means that they met at a point which was closer to calcutta than mumbai. Now, as they started at same time, Mumbai mail would have been faster to cross the half way point and meet calcutta mail . Therefore Mumbai mail speed should be higher than 48, which is 96 km/h

answer is D
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You can use hit and try method if more than one option is greater than 48.

Lets say answer is 96(option d). Now I will prove by contradiction,

Then mumbai to kolkata has to travel for 3 hrs after their meet  making distance= 288km.

Similary kolkata to mumbai after meet travelled for 12 hrs at 48kmph making diastance=576.

Now both train started journey same time and lets say they meet at time t,

then from s=d/t, as both train travel for same time when they meet we must get d1/s1=d2/s2 also d1+d2=d

So distance travelled by kolkata to mumbai must be 288km and distance travelled by mumbai to kolkatkolkata must be 576.

We get 288/48=576/96 which is true. Hence this option is correct answer.
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Two trains, Calcutta Mail and Bombay Mail, start at the same time from stations Kolkata and Mumbai respectively towards each other.After passing each other, they take 12 hours and 3 hours to reach Mumbai and Kolkata respectively. If the Calcutta mail is moving with the speed of 48 km/h , the speed of the Bombay mail is
ans:
-Two trains, Calcutta Mail and Bombay Mail,
-start at same time  from station Kolkata and Mumbai respectively toward each other,
-After passing each other they take 12 hours and 3 hours to reach Mumbai and Kolkata respectively Calcutta mail is -moving with the speed of 48 km/h

* the speed of the Bombay mail is?
48 * 12= 3 * speed
 192 km/hr is the speed of bombay mail.




how could it be 96?????????????????/

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