Multiple choice

How long does a train $110$ metres long running at the speed of $72\mathrm { km } /$ hr take to cross a bridge $132$ metres in length ?

  1. $9.8$ sec
  2. $12.1$ sec
  3. $12.42$ sec
  4. $14.3$ sec
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total distance = 110 + 132 = 242m. Speed = 72 km/hr = 72 * (5/18) = 20 m/s. Time = 242 / 20 = 12.1 seconds.

AI explanation

First, find the total distance the train must travel to cross the bridge, which is the sum of the train length and the bridge length, giving 110 m plus 132 m equals 242 m. Next, convert the speed of 72 km/hr to metres per second by multiplying by 5/18, yielding 20 m/s. Divide the total distance of 242 m by the speed of 20 m/s to find the time. The time taken to cross the bridge is 12.1 seconds.

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