Jim has a special keyboard with the alphabet and ten numbers. Jim is blindfolded and does not know the position of the keys. Determine the probablility if two keys are pressed and a number is pressed first and a letter second.

Question

Jim has a special keyboard with the alphabet and ten numbers.  Jim is blindfolded  and does not know the position of the keys.  Determine the probablility if two keys are pressed and a number is pressed first and a letter second.

drwls · Answer

There are 36 keys and the first strike of the keys has a 10/36 chance of being a number. On the second strike, he could hit any of the 36 keys, but only 26 are letters. So the answer is

10/36 x 25/36 = 0.1929

drwls · Answer

Make that 10/36 x 26/36 = 0.2006

David Q · Answer

Just a thought... if Jim holds down the first key while he presses the second, then he's only got 35 to choose from for his second press, which would slightly increase his chance of hitting a letter. But I don't think that's what the question meant.