There are 4 people who has to cross a stretch of 300 km. They normally run at a speed of 10 kmph. One of them has a bike that travels at 50 kmph. The bike first takes one person alone and crosses the stretch while the other two keep running. Then he comes back without wasting time and picks up another person from the way, drives him across the stretch, and does the same for the last person. How long does this whole process take?
after 115 minutes
after 20 minutes
24 hrs
58/3 hrs
Explanation:
Time taken to carry 2nd person = 300/50 = 6 hrs.
Time taken to meet 3rd person =(300-6*10)/(50+10) = 4 hrs
Time taken to carry 3rd person = 4 hours
Time taken to meet 4th person = (300 –140)/60 = 8/3
Total time = 6+4+4+8/3+8/3 = 58/3 hours
Time taken to carry 2nd person = 300/50 = 6 hrs.
Time taken to meet 3rd person =(300-6*10)/(50+10) = 4 hrs
Time taken to carry 3rd person = 4 hours
Time taken to meet 4th person = (300 –140)/60 = 8/3
Total time = 6+4+4+8/3+8/3 = 58/3 hours