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 3 of 7.
Ganesh Sang said:
1 decade ago
Please in every example we need to find samples or experiment samples or there is any shortcut for easily getting number of prime number or sum of two numbers as a prime ?
Bumba said:
1 decade ago
If we can chose (1,2) and (2,1) (2,3) and (3,2).
Then why we can't chose (1,1) both time. Not only that case we also chose (1,1) as a double event space. Please reply.
Then why we can't chose (1,1) both time. Not only that case we also chose (1,1) as a double event space. Please reply.
Azly said:
9 years ago
If we draw this in a cartesian plan we can easily find the answer. Take d axis and Y axis. Number from 1 to 6 in each axis. The find the sum of the numbers using plan.
Tahir amin said:
9 years ago
Please, Solve anyone this question. A committee of 3 is to be selected from a group of 5 girls and 3 boys. What is the probability that two boys are selected?
Vrushang said:
1 decade ago
Hey if you take 5, 6 and 6, 5 as a different pair then why you don't take (1, 1) and (1, 1) as different pairs because it is first time 1 and second time 1.
Williams said:
6 years ago
In the answer, why didn't they count (1,1) twice as it is possible that the number 1 might come on either of the dices, as they calculated (1,2) & (2,1)
Siva said:
1 decade ago
Prime number means the we gets only one time. i.e., 1*2=2 only once we get 2. But for 4 1*4=4, 2*2=4 now we get 4 for 2 times in-terms of multiplication.
Anil singh said:
1 decade ago
Prime number divisible by 1 and that nimber only but in the case (1,4), (1,6) etc divided by other number like 1,2,3
Please explain.
Please explain.
Ruthvik Gowda said:
5 years ago
Why (1, 1) conisdered only once ?
Since there is two dices we can get (1, 1) twice right, like this combination (2, 5) & (5, 2).
Since there is two dices we can get (1, 1) twice right, like this combination (2, 5) & (5, 2).
(2)
Olamikan adesanmi said:
1 decade ago
No wot they mean is that the sum (total) is a prime number. So as for (1, 4) , (1, 6) , the sum are 5 and 7 which are prime numbers.
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