Question

Sal has a small bag of candy containing three green candies and two red candies. While waiting for the bus, he ate two candies out of the bag, one after another, without looking. What is the probability that both candies were the same color?

Answer 1

`2/5` . Probabilities are usually given as a fraction.

This could also be expressed as `40%, 0.4, or "2 in 5"`

Explanation:

Remember that once he has eaten one candy, there is one less in the bag.

The candies could be "BOTH GREEN" or " BOTH RED"

`P("same") = P("GG") + P("RR")`

=`3/5xx2/4 + 2/5xx1/4`

=`6/20 + 2/20`

=`8/20 = 2/5`

Answer 2

The total probability of having both the same color is `2/5`

Explanation:

The best way to visualise this is with a probability tree:

When making the first choice there are 5 to chose from. Once this has been removed and the second choice is being made there are 4 to chose from. Hence the change in denominator.

The total probability of having both the same color is

`3/10+1/10 = 4/10 =2/5`