Suppose you ask a friend to randomly choose an integer between 1 and 10, inclusive. What is the probability that the number will be more than 3 or odd? (Enter your probability as a fraction.)

Answer 1

So we will assume and numbers are equally likely to be chosen by your friend so each number has a 10% chance of being chosen. The parameters we would like it to meet are:

x>3 (4, 5, 6, 7, 8, 9, 10)

x=odd (1, 3, 5, 7, 9)

Now lets combine those sets of numbers since we want either of those conditions to be true (OR):

(1, 3, 4, 5, 6, 7, 8, 9, 10)

we have every number listed except for 2, so we have 9 out of the 10 numbers he could choose:

There is a 9/10 chance your friend picks a number greater than 3 or an odd number between 1 and 10 inclusive