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
5
.
Event
B
: The sum is divisible by
5
.
2 answers
Answer
die a-> 1 2 3 4 5 6
die b
1
2
3
4
5
6
36 boxes
label them for the sum of number above and to the left
eg
2 3 4 5 ....7
3 4 5 7 ....8
4 5 ........9
etc
Now for example 6 of the boxes contains a sum less than 5
that means 30/36 are greater than five
of course 30/36 = 5/6
die b
1
2
3
4
5
6
36 boxes
label them for the sum of number above and to the left
eg
2 3 4 5 ....7
3 4 5 7 ....8
4 5 ........9
etc
Now for example 6 of the boxes contains a sum less than 5
that means 30/36 are greater than five
of course 30/36 = 5/6
1 answer