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 6 of 7.
Sirisha said:
7 years ago
1+1=2 here 2 is not a prime number then please explain why (1, 1) used here?
Explain, please.
Explain, please.
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)
Harika said:
6 years ago
Hi when would be the sample space be 12 and when would it be 36? I mean if a dice is thrown twice or if two dice are thrown. What would be the difference in the sample space?
Priyanka said:
6 years ago
Anyone tell me, why not taking (6, 3)?
Sweta said:
6 years ago
Are 4 and 6 prime numbers?
4 and 6 divisible by not only 1 and itself, but it is also divisible by 2, 3.
4 and 6 divisible by not only 1 and itself, but it is also divisible by 2, 3.
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)
Priya said:
5 years ago
@All.
Why here we perform addition operation to get a Prime number? Instead of getting total as prime we use (product or subtract).
Why only addition is performed? Can anybody explain this clearly!
Why here we perform addition operation to get a Prime number? Instead of getting total as prime we use (product or subtract).
Why only addition is performed? Can anybody explain this clearly!
Anu said:
5 years ago
@Sowmya.
Yes, the total score here means the sum of numbers.
Yes, the total score here means the sum of numbers.
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.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers