Each of the four sons can cross the bridge in time, namely 3, 7, 13, and 17 minutes, respectively, Only two people can cross at a time, What is the minimum time in which all four can cross the bridge?
A ) 28 minutes
B ) 20 minutes ✅
C ) 27 minutes
D ) 29 minutes
Explanation:
First, send 17 and 7. After 7 minutes, 7 is at finish and 17 needs 10 more minutes to complete his travel. now send 13. After 10 minutes 17 reaches finish and 13 needs 3 more minutes to complete. now send 3. Both 3 and 13 reach the destination at the same time after 3 minutes. hence the time taken is 7+10+3 = 20 minutes.