Question

Train a crosses a 320m pong platform in 42 sec train b which is 160 m long and running at 96 km/hr crosses train a 78/11 sec while running in opposite direction then find in how much time will train a cross a pole 1

Answer 1

Answer:

The train a take 10 sec to cross a pole.

Step-by-step explanation:

Let the speed of train a be x

and, the length of train a be y

given: speed of train b =96 km/hr=96×(5/18)m/sec

solution:

A/q-(320 + y)/x =42

320+y =42x

y=42x-320. -(eq.1)

(160+y)/(80/3 +x)= 78/11

cross multiplying ,we get

11(160+y)=78(80/3 +x)

1760 +11y=2080+ 78x

11y=78x +320. -(eq.2)

putting the value of y from eq.1 in eq.2,we get

11(42x-320)=78x + 320

462x-78x= 320 + (320 ×11)

384x =3840

x=10 m/sec

putting x=10 in eq.1,we get

y=420-320 =100m

To cross a pole train a take-

Time=(length of train a) /speed of train a

=y/x

=100/10

=10 sec