Bridge Crossing 2 Puzzle

Question:

John and his family members want to cross to the other side of the bridge at night. They have only one lamp which lasts for only 30 minutes. A maximum of only two persons can cross at one time, and they must have the lamp with them.

Each person walks at a different speed. John walks at a speed of 1 min, his brother jack walks at 3 min, his mother Julie walks at 6 min, his father Jeff walks at 8 min and his grandpa George walks at 12 min.

A pair must walk together at the rate of the slower person.

How can John�s family cross the bridge?

Solution:

First John and his brother Jack cross the bridge, which takes 3 minutes.

After this, John walks back with lamp, it takes 1 minute. Then Johns gives the lamp to his father Jeff and grandpa George.

Jeff and George cross the bridge with 12 minutes.

Jack returns back with the lamp, which takes 3 minutes and handover the lamp to john.

John and his mother Julie crosses the bridge, it takes 6 minutes.

Now again john takes the lamp and cross the bridge with 1 minute.

Finally John and Jack cross the bridge with 3 minutes.

Total = 3 + 1 + 12 + 3 + 6 + 1 + 3 = 29 minutes

There is 1 minute left!