probability

Question

An ordinary (fair) die is a cube with the numbers
1
through
6
on the sides (represented by painted spots). Imagine that such a die is rolled twice in succession and that the face values of the two rolls are added together. This sum is recorded as the outcome of a single trial of a random experiment.
Compute the probability of each of the following events:
Event
A
: The sum is greater than
6
.
Event
B
: The sum is divisible by
5
or
6
(or both).

Answer 1

7/12 and 13/36 for events

described

P(A) = P(7 through 12) = (6+5+4+3+2+1)'36 = 21/36= 7/12

P(B)= P(5, 6, 10, 12) = (4+5+3+1)/36 = 13/36

Answer 2

Prob( 7,8,9,10,11,12) = 6/36 + 5/36 + 4/36 + 3/26 + 2/36 + 1/36 = 21/36 = 7/12 = 0.583333.... = 58 and 1/3 %

 

Prob ( 5,6,10,12) = 4/36 + 5/26 + 3/36 + 1/36 = 13/36