You have a suitcase & the number lock of suitcase has 2 wheels, each labelled with digits 0-9. You do not remember the code or the sequence of 2 digits.
(1) What is probability that you open suitcase on first trial?
(2) There is no repetition in the digits of the code. Then total possible no. of trials to open suitcase is ____.
(1) What is probability that you open suitcase on first trial?
(2) There is no repetition in the digits of the code. Then total possible no. of trials to open suitcase is ____.
Answers & Comments
Answer:
There are 10 digits out of which we have to choose only 4 and no digit is repeated.
Thus we will apply :-
p \binom{10}{4}p(
4
10
)
=> 10!/(10-4)!
=> 10!/6! = 10×9×8×7×6!/6!
=> 5040
Hence total outcomes = 5040
Now lock will by one correct sequence hence
probability = 1/5040