Question 1203251
The possibility space consists of the integers from 1 to 20 inclusive.<pre>
That means the universal set U is all the integers from 1 through 20.
U = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20}</pre>
A is the event ' the number is a multiple of 3'.<pre>
That means A is the set of integers of U you get by counting by 3's.
A = {3,6,9,12,15,18}</pre>
B is the event 'the number is a multiple of 4'.<pre>
That means B' is the set of integers of U you get by counting by 4's.
B = {4,8,12,16,20}
B' = set of elements of U that are not in B ={1,2,3,5,6,7,9,10,11,13,14,15,17,18,19}

{{{"P(A)"}}}{{{""=""}}}{{{matrix(1,5,Number,of,elements,in,A)/matrix(1,5,Number,of,elements,in,U)}}}
{{{"P(B')"}}}{{{""=""}}}{{{matrix(1,5,Number,of,elements,in,"B'")/matrix(1,5,Number,of,elements,in,U)}}}

Count those numbers of elements and make those fractions.  Reduce the fractions if
possible.

Edwin</pre>