Elitmus
Exam
Numerical Ability
Probability
A person forgets two digits of user ID for a website. He remembers that two digits are odd. What is the probability of him typing the correct last digits by randomly typing 2 odd digits?
(1/25) (1/5) (1/2) (2/5)
Read Solution (Total 7)
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- 1/25
As only one correct from total 5*5 cases - 7 years agoHelpfull: Yes(15) No(1)
- The odd digits are odd or. 1,3,5,7,9
And two digits can be same ,so probability is (1/5)*(1/5)=1/25 - 7 years agoHelpfull: Yes(10) No(1)
- No of odd digits between 0 to 9 is= 5 (1,3,5,7,9)
Favorable case of selecting 2 odd digits is p(A) = 5C2 = 10
and sample case of arranging two odd digits is p(S) = 5*4 = 20
So,
Probability p(N) = p(A) / p(S) = 10 / 20 = 1/2 Answer - 7 years agoHelpfull: Yes(3) No(15)
- no of odd digits =1,3,5,7,9
sample space 5*5 as they said only odd the number it might be repeated.
p=5c2/5*5=2/5. - 7 years agoHelpfull: Yes(1) No(7)
- probability= 5c2/25= 2/5
- 4 years agoHelpfull: Yes(1) No(0)
- The total possibilty of selecting 2 numbers in a way(11,13,15,....) = 5*5
Now, Out of these only 1 is correct.
Prob = Favourable Outcome/ Total Outcome
Ans = 1/25 - 4 years agoHelpfull: Yes(0) No(0)
- No of odd digits between 0 to 9 is= 5 (1,3,5,7,9)
Favorable case of selecting 2 odd digits is p(A) = 5C2 = 10
and sample case of arranging two odd digits is p(S) = 5*4 = 20
So, Probability p(N) = p(A) / p(S) = 10 / 20 = 1/2 Answer - 1 year agoHelpfull: Yes(0) No(0)
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