exam
Maths Puzzle
Two identical trains A and B running in opposite direction at same speed tale 2 min to cross each other completely. The number of bogies of A are increased from 12 to 16. How much more time would they now require to cross each other?
A.
40 sec
B.
50 sec
C.
60 sec
D.
20 sec
Read Solution (Total 1)
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- consider each bogie of train to be 10m,so being identical lengths of train L1=L2=120
they take 2min to cross each other completely=> time t=2min=120sec
so, v1+v2=(L1+L2)/time to cross each other ( V1=V2=v)
2v=(120+120)/120=>v=1m/s
now bogies of a is increased frm 12 to 16 =>L1=160 & L2=120
now ,t=(L1+L2)/(V1+V2)
=>t=160+120/2
t=140 sec
therfore 140-120=20 sec more time is required to cross each other - 9 years agoHelpfull: Yes(0) No(0)
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