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30 Jun 2025, 11:46
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It's actually pretty easy, if you take the reverse probability
asked:- what is the probability of getting an even sum ?
so, probability of getting an even sum would also mean not getting an odd sum. Hence from the total probability of 1 if we subtract getting a sum of odd, we should have "probability of getting an even sum".
solution:-
given 4 dice
1 = P(sum even) + P (sum odd)
getting a sum even meaning :
P(sum even) = 1- P(sum odd)
ways to get odd = either we get [o*o*o*e] or we get [o*e*e*e]
remember to arrange the above odds and evens in 4!/3! ways.
in a dice there are 3 even (2,4,6) and 3 odd numbers (1,3,5)
hence,
=> 1 - [(o*o*o*e)*4!/3! + (o*e*e*e)*4!/3!]
=> 1 - [3/6*3/6*3/6*3/6*4!/2!*2].............. solving this gets....
=> 1 - 2/4
=> 1/2 (option B)
asked:- what is the probability of getting an even sum ?
so, probability of getting an even sum would also mean not getting an odd sum. Hence from the total probability of 1 if we subtract getting a sum of odd, we should have "probability of getting an even sum".
solution:-
given 4 dice
1 = P(sum even) + P (sum odd)
getting a sum even meaning :
P(sum even) = 1- P(sum odd)
ways to get odd = either we get [o*o*o*e] or we get [o*e*e*e]
remember to arrange the above odds and evens in 4!/3! ways.
in a dice there are 3 even (2,4,6) and 3 odd numbers (1,3,5)
hence,
=> 1 - [(o*o*o*e)*4!/3! + (o*e*e*e)*4!/3!]
=> 1 - [3/6*3/6*3/6*3/6*4!/2!*2].............. solving this gets....
=> 1 - 2/4
=> 1/2 (option B)
05 Jul 2025, 04:01
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Just think logically.
How will you arrive at an even sum if you have 2 figures? Either both will be even or both will be odd =
EE or OO
What are the other variations where an odd sum is arrived at? EO or OE
Therefore, 2 out of 4 cases will have an even sum. Probability = 2/4 = 1/2
The same rule applies when you are summing up 4 figures because 4 is a multiple of 2, so the probability will be the same.
Ans B.
How will you arrive at an even sum if you have 2 figures? Either both will be even or both will be odd =
EE or OO
What are the other variations where an odd sum is arrived at? EO or OE
Therefore, 2 out of 4 cases will have an even sum. Probability = 2/4 = 1/2
The same rule applies when you are summing up 4 figures because 4 is a multiple of 2, so the probability will be the same.
Ans B.
19 Aug 2025, 08:17
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Probability of getting even sum in two dice will be equal to probability of getting even sum in 4 dice.
Odd -> O
Even -> E
O + O = E
O + E = O
E + O = O
E + E = E
Prob(Even Sum) = 2/4 = 1/2
Odd -> O
Even -> E
O + O = E
O + E = O
E + O = O
E + E = E
Prob(Even Sum) = 2/4 = 1/2
