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 The Safe (Posted on 2003-08-11)
A group of crazy bank robbers try to crack a safe, even though they don't have a clue what the code is. The code has 5 numbers in, and the numbers on the dial range from 1 to 60. If they crack the safe, they get £100 billion.(That's a British billion - a million million). If they get the code wrong, they get caught and fined £1 million.

Assuming the bank robbers don't enter the same code twice, if they keep trying and re-trying until they crack the safe, are they more likely to have lost or gained money? If so, how much would they probably gain/lose?

 Submitted by Lewis Rating: 2.7500 (4 votes) Solution: (Hide) The amount of possible combinations is 60*60*60*60*60, which is 777,600,000. There is an equal chance of getting it on the first go as there is getting it on the last go - which is 1 in 777,600,000. After trying half of that many times - 388,800,000 - there will be a 50% chance that they will have cracked the code and a 50% chance that they will not have cracked the code. So the average amount of tries it will take is 388,800,000. If they get fined £1 million 388,800,000 times this will mean a total lose of £388,800,000,000,000. When they crack the safe they will get £100,000,000,000,000. Now take this money away from their losses and you get £288,800,000,000,000, which is the average amount of money that they will lose.

 Subject Author Date Something odd gabbo 2004-09-16 00:06:15 my solution is redundant Bart freeman 2003-09-20 13:24:48 correct me if i'm wrong Bart freeman 2003-09-20 13:14:46 No Subject Dave Cheetham 2003-08-17 13:12:19 re: solution Brian Wainscott 2003-08-12 15:22:15 re: daniel's solution Daniel 2003-08-11 17:25:09 solution Daniel 2003-08-11 17:13:20 code versus using it? Gamer 2003-08-11 12:33:39 re: solution Sanjay 2003-08-11 10:23:44 solution Charlie 2003-08-11 09:43:59

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