Brain Teasers
Family Crossing Bridge
It is a dark night and there is a family of 5 that needs to cross a bridge suspended over a deep valley. The only light available was a lamp which could only burn for 30 minutes. Up to two members can cross each time. Different members take different amount of time to cross and the time they take must be at the pace of the slower one. The time taken for each member is as shown:
(G)Grandpa - 12 mins
(F)Father - 8 mins
(M)Mother - 6 mins
(S)Sister - 3 mins
(B)Brother - 1 min
For example, if the father and the grandpa were to cross together, it would take 12 minutes, leaving 18 minutes for one of them to return and get the rest moving.
Can you help the family to get across?
(G)Grandpa - 12 mins
(F)Father - 8 mins
(M)Mother - 6 mins
(S)Sister - 3 mins
(B)Brother - 1 min
For example, if the father and the grandpa were to cross together, it would take 12 minutes, leaving 18 minutes for one of them to return and get the rest moving.
Can you help the family to get across?
Hint
The brother helps well in bringing the lamp to and fro with his speed.Answer
B+S Cross = 27 mins remainB Back = 26 mins remain
B+M Cross = 20 mins remain
S Back = 17 mins remain
F+G Cross = 5 mins remain
B Back = 4 mins remain
B+S Cross = 1 min remains.
The family reunites at the other end, leaving 1 minute of light to be happy.
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