Question

An electrician disconnected 5 wires of different colors from their respective connections and forgot the order in which they were placed. Assuming you connect them by trying different sorts and that the last one is correct, how many tries must you do before getting it right?

Answer 1

120 tries

Explanation:

You can try 5 different wires in the first connection.

Then you have 4 wires left, so you try 4 wires in the second connection. Remember, you are now trying 4 wires for each of the first 5, so up to here you already made 4 * 5 tries = 20 tries.

Next you try 3, then 2, then you have 1 left.

Number of tries: 5 * 4 * 3 * 2 * 1 = 120

Answer: 120 tries