A family is trapped in a jungle. There is a bridge which can lead them to safety. But at one time, the bridge can only allow two people to pass through. Also, all of them are afraid of the dark and thus, they can’t go alone.
Father takes 1 minute to cross, mother takes 2 minutes, son takes 4 and the daughter takes 5 minutes. While crossing the time taken will be according to the slower one. How can they all reach at the other side in the minimum possible time ?
Father and Mother goes first: 2 minutes.
Father comes back: 2+1 = 3 minutes.
Both children go to mother: 3 + 5 = 8 minutes.
Mother comes back to Father: 8 + 2 = 10 minutes.
Mother and Father go: 10 + 2 = 12 minutes.
Thus, all of them reach the other sides in 12 minutes.