Aptitude - Probability - Discussion
Discussion Forum : Probability - General Questions (Q.No. 10)
10.
Two dice are tossed. The probability that the total score is a prime number is:
Answer: Option
Explanation:
Clearly, n(S) = (6 x 6) = 36.
Let E = Event that the sum is a prime number.
| Then E | = { (1, 1), (1, 2), (1, 4), (1, 6), (2, 1), (2, 3), (2, 5), (3, 2), (3, 4), (4, 1), (4, 3), (5, 2), (5, 6), (6, 1), (6, 5) } |
n(E) = 15.
| P(E) = |
n(E) | = | 15 | = | 5 | . |
| n(S) | 36 | 12 |
Discussion:
64 comments Page 4 of 7.
Trisha said:
5 years ago
@Rutvik.
There (1,1) consider only once because there is no difference between 1, 1 or 1, 1, but there is always a difference between 2, 5 or 5, 2.
Suppose dice 1 and dice 2 have the same no. Like (1, 1) how will you differentiate dice 1 and 2 but if the no. Are change like (1, 2) (2, 1) or (5, 2) (2, 5) you will differentiate dice 1 and 2. That's why.
I hope now you will understand.
There (1,1) consider only once because there is no difference between 1, 1 or 1, 1, but there is always a difference between 2, 5 or 5, 2.
Suppose dice 1 and dice 2 have the same no. Like (1, 1) how will you differentiate dice 1 and 2 but if the no. Are change like (1, 2) (2, 1) or (5, 2) (2, 5) you will differentiate dice 1 and 2. That's why.
I hope now you will understand.
Maths said:
3 years ago
1 is not a prime number.
So, the correct answer is 14/36 = 7/18.
So, the correct answer is 14/36 = 7/18.
Deepak said:
4 months ago
We get the number from the first dice = 1,2,3,4,5,6
And the same from the second dice.
We have prime numbers in both dice is 1, 2, 3, 4, 5 and a total of 1+2=3 is a prime number.
So, total 12.
We have 5 prime numbers and a total score number.
So, 5/12 is the answer.
And the same from the second dice.
We have prime numbers in both dice is 1, 2, 3, 4, 5 and a total of 1+2=3 is a prime number.
So, total 12.
We have 5 prime numbers and a total score number.
So, 5/12 is the answer.
Amit said:
1 decade ago
Why (1, 1) don't consider two times while sets like (1, 2) n (2, 1) is taken two times?
Srinivas said:
1 decade ago
Hi sir, i am little bit poor in maths, what is the meaning of prime numbers...
{ (1, 1), (1, 2), (1, 4), (1, 6), (2, 1), (2, 3), (2, 5), (3, 2), (3, 4), (4, 1), (4, 3),
(5, 2), (5, 6), (6, 1), (6, 5) }
Why do choose those no only ?
Why don't you choose (6,6) (2,2)n etc
{ (1, 1), (1, 2), (1, 4), (1, 6), (2, 1), (2, 3), (2, 5), (3, 2), (3, 4), (4, 1), (4, 3),
(5, 2), (5, 6), (6, 1), (6, 5) }
Why do choose those no only ?
Why don't you choose (6,6) (2,2)n etc
Nachiket said:
1 decade ago
Prime number is a number which is divisible by 1 and that number only.
DEBAI said:
1 decade ago
Hi RAM, if you tossed 2 dice then you get total 6x6 ie 36 possible cases (equallay likely cases) the above mentioned 15points are prime nos (2, 3, 5, 7, 11, 13, 17, 19. ) if you add any one out of 15 get prime no. That's all.
Sujatha said:
1 decade ago
Could you please tel me any short methods for Probability?
Harshini said:
1 decade ago
Please tel me where to use permutation and where to use combinations. ?
Prasad said:
1 decade ago
Hey why we cant take (1,3),(2,2,),(3,1)etc we can take others also na?
So please solve this in easy way.
So please solve this in easy way.
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