Brain Teasers
PIN the PIN !!!
Akash was trying to remember the PIN of his credit card. The PIN consisted of four characters, three of which were digits from 0 to 9 and one of which was a letter of the alphabet. If Akash can try different possibilities at the rate of 5 possibilities per minute and he works for 8 hours a day everyday, then find out the number of days in which he can try out all the combinations possible for the PIN.
Answer
The number of days required to try all the combinations is 43 1/3 days.The four character code consists of 3 digits 0 to 9 and 1 letter of the alphabet A to Z.
Let us assume the first character of the PIN to be an alphabet and the remaining three characters to be digits.
Then the number of possible PINs
= 26*10*10*10
This is the number of PINs with the first character of the PIN being an alphabet.
However we can have the alphabet as the second character, third character or fourth character of the PIN. Thus there are four different combinations.
Hence the total number of such four character PINS available
= 4*26*10*10*10 = 104000.
At the rate of 5 possibilities, taking 8 hours a day, Akash would take
104000/(5*60*8) =
104000/(300*8) = 43 1/3 days.
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Comments
Each character has 36 possiblities. 26 letters and 10 numbers. So wouldn't the total be 36*36*36*36?
No, it can't be 36*36*36*36 coz this will have possibilities wherein all 4 characters are numbers and the PIN consists of 1 alphabet and 3 numbers.
Pretty good problem, quite easy to do though.
easy!?!?!?!, I can't get these things, might just be because I haven't learned this stuff yet, but i'm very good at other types of teasers
High school maths problem.
all you need to have is basic knowledge on probability.and the division part need not to mention.
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