Question

Two trains running in opposite directions cross each other in 22 seconds and a pole on the platform in 25 seconds and 15 seconds respectively. The ratio of their speeds is: *

Answer 1

Answer:

L1 / V1 = 25       time for train 1 to pass pole

L2 / V2 = 15      time for train 2 to pass pole

(L1 + L2) / (V1 + V2) = 22    the total length of two trains divided by

                                            their relative speed

(25 V1 + 15 V2) / (V1 + V2) = 22

3 V1 = 7 V2

V1 = 7 / 3 * V2

Answer 2

Answer: The ratio of their speeds would be $3:7$

Step-by-step explanation:

Since we have given that

Time taken by two trains cross each other = 22 seconds

Time taken by first train to cross pole = 25 seconds

Time taken by second train to cross pole = 15 seconds

So, the ratio of their time is given by

$\dfrac{L_1}{V_1}25\\\\\dfrac{L_2}{V_2}=15\\\\\dfrac{L_1+L_2}{V_1+V_2}=22\\\\\dfrac{25V_1+15V_2}{V_1+V_2}=22\\\\25V_1+15V-2=22V_1+22V_2\\\\3V_1=7V_2\\\\\dfrac{V_1}{V-2}=\dfrac{7}{3}$

So, the ratio of their speeds would be

$3:7$