A number from 1 to 10 is chosen at random. What is the probability of choosing a 5 or an even number?

The numebers chosen are from 1 to
10.

Then possible outcomes are:
1,2,3,4,5,6,7,8,9,10

The probability of chosen a 5  OR and
even number = probability of chosen a 5  + probability of chosen an even
number.

Let us calculate each
event:

P ( 5) = 1/10

Even
number are: 2,4,6,8,10

==> P(even) =
5/10

Then :

P( 5 OR even) =
P(5) + P(even)

                       = 1/10 + 5/10 =
6/10

                       =
3/5

==> P ( 5 or even) =
3/5