One family wants to get through a tunnel.
Dad can make it in 1 minute, Mom in 2 minutes, Son in 4 minutes and Daughter in 5 minutes.
Unfortunately, not more than two persons can go through the narrow tunnel at one time,
moving at the speed of the slower one.
Can they all make it to the other side,
if they have a torch that lasts only 12 minutes
and they are afraid of the dark?
Explain your answer.
Yes they can make it to the other side of the tunnel in 12 minutes.
First Mom and Dad will go.(2 min)
Dad will come back with torch(1 min)
Son and Daughter will go.(5 min)
Mom will come back with torch(2 min)
and finally Mom and Dad will go(2 min)
So the family will get through the tunnel in 2+1+5+2+2 = 12 min