Question

A box contains 5 red, 2 white, & 3 blue marbles. If a marble is selected at random, what is the probability that it is red or white?

Answer 1

`7/10`

Explanation:

Probability that it is red =`5/10`
Probability that it is white =`2/10`

So the probability that it is red or white =`5/10+2/10=7/10`

Another way

Probability that it is red or white is the same as it NOT being blue
Probability that it is blue =`3/10`, so the probability that it is NOT blue =`1-3/10=7/10`