Aptitude - Probability - Discussion
Discussion Forum : Probability - General Questions (Q.No. 4)
4.
What is the probability of getting a sum 9 from two throws of a dice?
Answer: Option
Explanation:
In two throws of a dice, n(S) = (6 x 6) = 36.
Let E = event of getting a sum ={(3, 6), (4, 5), (5, 4), (6, 3)}.
 P(E) = |
n(E) | = | 4 | = | 1 | . |
| n(S) | 36 | 9 |
Discussion:
52 comments Page 4 of 6.
Deepthi said:
9 years ago
By throwing 2 dies, to get a sum of 9 there are also possibilities of getting (1,8) (2,7) (3,6) (4,5) (5,4) (6,3) (7,2) (8,1) we have 8 possibilities please explain this.
Naimulsamad said:
9 years ago
Look in a dice there are number 1, 2, 3, 4, 5, 6.
To form as a 9 we need 6 + 5 + 4 + 3 number. Such as 5 + 4 = 9, 6 + 3 = 9 but 1 + 8 or 2 + 7 is not possible because dice do not contain the number 7, 8.
So sum up the number 6 +5 + 4 + 3 = 18 (one dice). 18 * 2 = 36 (two dice).
To form as a 9 we need 6 + 5 + 4 + 3 number. Such as 5 + 4 = 9, 6 + 3 = 9 but 1 + 8 or 2 + 7 is not possible because dice do not contain the number 7, 8.
So sum up the number 6 +5 + 4 + 3 = 18 (one dice). 18 * 2 = 36 (two dice).
(1)
Chethan said:
9 years ago
Why they took n(E)/n(S)? In some other problem, they took n(S)/n(E).
Umar said:
9 years ago
9 + 9 = 18,
=> 2/18 = 1/9.
=> 2/18 = 1/9.
B.lokesh said:
9 years ago
One dice means 6 faces.
Two dice means 6 * 6 = 36 faces.
Either,
(1,1)(1,2)(1,3)(1,4)(1,5)(1,6)
(2,1)(2,2)(2,3)(2,4)(2,5)(2,6)
(3,1)(3,2)(3,3)(3,4)(3,5)(3,6)
(4,1)(4,2)(4,3)(4,4)(4,5)(4,6)
(5,1)(5,2)(5,3)(5,4)(5,5)(5,6)
(6,1)(6,2)(6,3)(6,4)(6,5)(6,6)
Total = 36 outcomes.
So question ask that,
Sum =9.
So,
3 + 6 = 9 (3,6)
6 + 3 = 9 (6,3)
4 + 5 = 9 (4,5)
5 + 4 = 9 (5,4)
4 out comes.
p = num of outcomes/total outcomes.
p = 4/36 = 1/9.
Hope you understand this.
Two dice means 6 * 6 = 36 faces.
Either,
(1,1)(1,2)(1,3)(1,4)(1,5)(1,6)
(2,1)(2,2)(2,3)(2,4)(2,5)(2,6)
(3,1)(3,2)(3,3)(3,4)(3,5)(3,6)
(4,1)(4,2)(4,3)(4,4)(4,5)(4,6)
(5,1)(5,2)(5,3)(5,4)(5,5)(5,6)
(6,1)(6,2)(6,3)(6,4)(6,5)(6,6)
Total = 36 outcomes.
So question ask that,
Sum =9.
So,
3 + 6 = 9 (3,6)
6 + 3 = 9 (6,3)
4 + 5 = 9 (4,5)
5 + 4 = 9 (5,4)
4 out comes.
p = num of outcomes/total outcomes.
p = 4/36 = 1/9.
Hope you understand this.
(6)
Shankar said:
9 years ago
Thanks for your solution @Sreejith.
Harini said:
9 years ago
How could n (S) be 36?
Yallaling Dashavant said:
9 years ago
Sum 9 means (1,8)(2,7)(3,6)(4,5)(5,4)(6 3)(7,2).
Means 8/36 = 2/9.
Means 8/36 = 2/9.
Sarita said:
9 years ago
How can it be 6x6?
Two throws of a dice mean 6+6. Your answer can only be till 12, not 36.
Two throws of a dice mean 6+6. Your answer can only be till 12, not 36.
Neetu Sanghvi said:
9 years ago
I agree @Sree Tulasi.
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