Question
Two trains of same length are running in parallel tracks
in the same direction with speed 65 km/hr and 95 km/hr respectively. The latter completely crosses the former in 30 seconds. Find the length of each train (in m).Solution
When two trains cross each other, they cover distance equal to the sum of their lengths with relative speed.  Let's take length of each train = x So, total length of both trains = 2x Relative speed = (95 – 65) × (5/18) = 25/3 m/sec. ∴ Total length = Time × Relative speed ⇒  2x = (30 × 25)/3 ⇒  x = 125 m
What will come in the place of questions (?) mark in the following questions.
1279, 1265, ? , 1225, 1193, 1149
What will come in place of (?) question mark in the given number series.
12, 27, 44, 65, ?, 139
25, 30, 50, 60, 80, ?Â
16, 20, 11, 27, ?, 38
21, 28, 39, 52, ?, 88
63 131 267 ? 1083 2171
?, 15, 45, 225, 1575, 14175
What will come in place of (?) question mark in the given number series.
52, 61, 79, 106, 142, ?Â
Find the missing number in the given number series.
512, 128, 32, 8, ?, 1-1, 5, 23, 59, ?
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