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GATE 2017 EC – Question 8

General Aptitude · Quantitative Aptitude: Arithmetic and Number Computation · 2 marks · Multiple choice

Trucks (10 m long) and cars (5 m long) go on a single lane bridge. There must be a gap of at least 20 m after each truck and a gap of at least 15 m after each car. Trucks and cars travel at a speed of 36 km/h. If cars and trucks go alternately, what is the maximum number of vehicles that can use the bridge in one hour?

  1. 1440
  2. 1200
  3. 720
  4. 600

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Correct answer: (A) 1440

Explanation

One truck and one car take $10 + 20 + 5 + 15 = 50$ m of road. At 36 km/h the traffic moves 36,000 m in an hour, so $\frac{36000}{50} = 720$ pairs pass, which is $720 \times 2 = 1440$ vehicles.