Ask Questions, Get Answers

Want to ask us a question? Click here
Browse Questions
Home  >>  CBSE XI  >>  Math  >>  Probability
0 votes

The number lock of a suitcase has four wheels,each labelled with 10 digits (ie) from 0 to 9.The lock opens with a sequence of four digits with no repeats.What is the probability of a person getting the right sequence to open the suitcase?

$\begin{array}{1 1}(A)\;\large\frac{1}{5040}\\(B)\;\large\frac{2}{4035}\\(C)\;\large\frac{3}{5040}\\(D)\;\text{None of these}\end{array} $

Can you answer this question?

1 Answer

0 votes
  • Required probability =$\large\frac{n(E)}{n(S)}$
Step 1:
Given repetition is not allowed.
$\therefore$ First place can be filled in 10 ways.
Second place can be filled in 9 ways.
Third place can be filled in 8 ways
Fourth place can be filled in 7 ways
$\therefore$ Total number of ways =$10\times 9\times 8\times 7$
$\Rightarrow 5040$ ways
Step 2:
Total number of outcomes n(S)=5040
Only one sequence will be right which will open the lock
No of favorable cases n(E)=1
Required probability=$\large\frac{n(E)}{n(S)}$
$\Rightarrow \large\frac{1}{5040}$
Hence (A) is the correct answer.
answered Jul 7, 2014 by sreemathi.v

Related questions

Ask Question
student study plans
JEE MAIN, CBSE, AIPMT Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App