When two dice are rolled what is the probability of getting a sum less than 6 ?

1 Answer
EZ as pi
Apr 30, 2018

#5/18#

Explanation:

The easiest method is to draw a possibility space first.
The grid shows the totals for two dice.

#6|" "7" "8" "9" "10" "11" "12#
#5|" "6" "7" "8" "9" "10" "11#
#4|" "color(blue)(5)" "6" "7" "8" "9" "10#
#3|" "color(blue)(4" "5)" "6" "7" "8" "9#
#2|" "color(blue)(3" "4" "5)" "6" "7" "8#
#1|ul(" "color(blue)(2" "3" "4" "5)" "6" "7)#
#color(white)(xxxx)1" "2" "3" "4" "5" "6#

There are: # 6xx6 = 36# possible outcomes.
Of these there are #color(blue)(10)# totals which are less than #6#.

#:.P("less than 6") = 10/36 = 5/18#

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