Pascal's Triangle
| We can use Pascal's Triangle to help us find the probability of multiple
events when there are only two outcomes. Each
side of the table represents one of two choices, and the numbers from
left to right signify the number of true outcomes for those choices. Each
row is labeled with its stage in the experiment. The total of the numbers
added across one row gives the sample space for that experiment.
EXAMPLE What is the probability in a family with five children that all five are girls? We look at the fifth row (5 children) of the chart. We label from the left side 5 girls, 4 girls, 3 girls, etc across the row to zero girls. We choose the first number in the row and divide this number by the total outcomes, found from adding up the numbers across the entire row. Thus P(5 girls) = 1/32.
EXAMPLE What is the probability of tossing four coins and getting the following results? We look at the row four and label the numbers no heads, one head, two heads, etc across the row. P(3 heads) = 4/16 |