joannabanana wrote:Find the probability of total score of 7 when rolling 3 dice
[spoiler]
ans 5/72 [/spoiler]
P = good/total
Total number of ways to roll a die 3 times = 6^3 = 216.
A good outcome is a sum of 7:
1+1+5=7. Number of ways to arrange 1,1,5 = 3!/2! = 3.
1+2+4=7. Number of ways to arrange 1,2,4 = 3! = 6.
2+2+3=7. Number of ways to arrange 2,2,3 = 3!/2! = 3.
3+3+1=7. Number of ways to arrange 3,3,1 = 3!/2! = 3.
Good outcomes = 3+6+3+3 = 15.
P(sum of 7) = 15/216 = 5/72.
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