Latest Infosys Aptitude Question SOLUTION: If two dice are rolled to obtain a sum or 5 or 7 what is the probability of getting 5 before 7?

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If two dice are rolled to obtain a sum or 5 or 7 what is the probability of getting 5 before 7?

Asked In Infosys asxa asxaxax (10 years ago)

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Read Solution (5) :

Dilip Kumar  (10 years ago)

Total no. of outcomes to obtain 5 or 7 is 10 on rolled of two dice. getting sum 5 before sum 7 is 4.so,
prob=4/10 i.e 2/5

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cheri ravi  (10 years ago)

2/5
4/36 / 4/36+6/36

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mohammad zahid  (10 years ago)

At each throw we have:

Probability of 5 = 4/36 = 1/9 Probability of 7 = 6/36 = 1/6

Probability of no result = 1 - (1/9 + 1/6)

= 13/18
:
now probability for getting 5 or 7 as sum wd gtting 5 before is

p = 1/9 + (13/18)(1/9) + (13/18)^2(1/9) + (13/18)^3(1/9) + ...

= (1/9)[1 + 13/18 + (13/18)^2 + (13/18)^3 + ...... ]

This is a GP with common ratio 13/18

= (1/9)/[1 -13/18]

= (1/9)/(5/18)

= 2/5

A

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priyanka  (9 years ago)

probability of getting a before b is =p(a)/(p(a)+p(b))
here p(a)=4/36
p(b)=p(7)=6/36
ans=2/5

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Raktim Tarafdar  (9 years ago)

probability of getting a sum of 5 or 7 is 10/36
and probability of getting 5 before 7 is 4/36 = 1/9

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