Higher Concepts of Mathematics
First, determine the number of possible outcomes. In this case, there are 6 possible
outcomes. From the stated problem, the roll is a success only if a 3 is rolled. There is
only 1 success outcome and 5 failures. Therefore,
In calculating probability, the probability of a series of independent events equals the product of
probability of the individual events.
Using a die, what is the probability of rolling two 3s in a row?
From the previous example, there is a 1/6 chance of rolling a three on a single throw.
Therefore, the chance of rolling two threes is:
1/6 x 1/6 = 1/36
one in 36 tries.
An elementary game is played by rolling a die and drawing a ball from a bag containing
3 white and 7 black balls. The player wins whenever he rolls a number less than 4 and
draws a black ball. What is the probability of winning in the first attempt?
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%.