Example of Probability:

Example:

By using a die, what is the probability of rolling two 3s in a row?

Solution:

From the previous example, there is a 1/6 chance of rolling a three on a single throw. Thus, the chance of rolling two threes is:

1/6 x 1/6 = 1/36 one in 36 tries.

Example:

An elementary game is played through rolling a die and drawing a ball from a bag holding 3 white and 7 black balls. The player wins while he rolls a number less than 4 and draws a black ball.  What is the probability of winning in the first attempt?

Solution:

There are 3 successful outcomes for rolling less than a 4, (i.e. 1,2,3).  The probability of rolling a 3 or less is:

3/(3+3) = 3/6 = 1/2 or 50%.

A probability of drawing a black ball is:

7/(7+3) = 7/10.

Thus, the probability of both events happening at the similar time is:

7/10 x 1/2 = 7/20.