TED-ED: Can you solve the river crossing riddle? - Lisa Winer

The video presents a problem where three lions and three wildebeest must cross a crocodile-infested river using a raft that can carry two animals at a time. The challenge is to ensure that lions never outnumber wildebeest on either side of the river. The video explores different crossing options and provides a step-by-step solution to get all animals across safely in eleven trips. The solution involves strategic planning to avoid any situation where the lions could eat the wildebeest. The video concludes with the animals safely reaching the other side, highlighting the importance of careful decision-making.

What is the main challenge the animals face when crossing the river?

• Ensuring lions do not outnumber wildebeest on either side

• Finding a raft that can carry all animals at once

• Crossing the river before nightfall

• Avoiding crocodiles in the river

Why can't two wildebeest cross the river first?

• The lions would refuse to row the raft

• The raft can only carry one animal at a time

• The remaining wildebeest would be outnumbered and eaten

• The raft would sink with two wildebeest

What is a viable first move to start solving the river crossing problem?

• Send two wildebeest across

• Send two lions across

• Send one lion and one wildebeest across

• Send one wildebeest across

What happens after two wildebeest cross the river?

• They are outnumbered and eaten

• They stay on the left bank with safety in numbers

• They wait for a lion to join them

• They return immediately to the right bank

How many total trips are needed to get all animals across the river safely?

• Eleven trips

• Twelve trips

• Ten trips

• Nine trips