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2 trains running in oppsite directions cross a stationary lady standing at a point named F in 26 seconds and 21 seconds respectively. Further, the 2 trains cross each other in 24 seconds. Determine the ratio of the speed of the 2 trains?

Solution

✅ Correct Option: 3

Two trains running in opposite directions cross a stationary lady standing at point F in 26 seconds and 21 seconds respectively. The two trains cross each other in 24 seconds.

Let the speeds of Train 1 and Train 2 be v1v_1 and v2v_2 respectively.

Let the lengths of Train 1 and Train 2 be L1L_1 and L2L_2 respectively.


When a train passes a stationary person, the train travels a distance equal to its own length.

For Train 1:

L1=v1×26L_1 = v_1 \times 26

L1=26v1L_1 = 26v_1 ... (1)

For Train 2:

L2=v2×21L_2 = v_2 \times 21

L2=21v2L_2 = 21v_2 ... (2)


When the two trains cross each other while moving in opposite directions, their relative speed is v1+v2v_1 + v_2.

The combined distance covered is L1+L2L_1 + L_2 in 24 seconds.

L1+L2=(v1+v2)×24L_1 + L_2 = (v_1 + v_2) \times 24 ... (3)


Substituting (1) and (2) into (3):

26v1+21v2=24(v1+v2)26v_1 + 21v_2 = 24(v_1 + v_2)

26v1+21v2=24v1+24v226v_1 + 21v_2 = 24v_1 + 24v_2

26v1−24v1=24v2−21v226v_1 - 24v_1 = 24v_2 - 21v_2

2v1=3v22v_1 = 3v_2

v1v2=32\dfrac{v_1}{v_2} = \dfrac{3}{2}

Therefore, the ratio of the speeds of the two trains is 3:23:2.

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