Question
Time is taken by two trains running in opposite
directions to cross a man standing on the platform in 36 seconds and 21 seconds respectively. It took 27 seconds for the trains to cross each other. What is the ratio of their speeds?Solution
Let the speed one train be x m/s and the speed of the second train be y m/s. Length of the first train = Speed × Time = 36x Length of second train = Speed × Time = 21y So, {(36x + 21y)/(x+y)} = 27 ⇒  36x + 21y = 27x + 27y ⇒ 9x = 6y Therefore, x:y = 2:3
612, 487,?, 396, 388, 387
Find the missing number in the given number series.
1, 2, 6, 24, 120, ?What will come in place of the question mark (?) in the following series?
36, 85, ?, 230, 330, 451
Find the missing term in the series:
2, 5, 11, 23, 47, ?
What will come in place of the question mark (?) in the following series?
400, 841, 1202, ?, 1716, 1885
44   45    41   50    ?      59    23
...221, 100, 0, -81, ?
...900 Â Â Â 90Â Â Â 18Â Â Â ? Â Â Â Â 2.16Â Â Â Â 1.08
16, 20, 11, 27, ?, 38
37, 57, 82, ?, 147, 187
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