7, 8, and then, choose the middle values 3 and 5.
{2, 4, 6, 8, . . . }
5
Find the average of the numbers 3 and 5: 3 +
2
= 4. The answer is 4.
The positive odd integers are:
{1, 3, 5, 7, . . . }
The mode of a set of numbers is the number that
occurs the greatest number of times.
If we were to combine the set of positive even
Example:
numbers with the set of positive odd numbers, we
would have the union of the sets:
For the number set 1, 2, 5, 3, 4, 2, 3, 6, 3, 7, the
number 3 is the mode because it occurs the
{1, 2, 3, 4, 5, . . . }
most number of times.
The symbol for union is: ∪.
Percent
A percent is a measure of a part to a whole, with the
Mean, Median, and Mode
whole being equal to 100.
To find the average or mean of a set of numbers, add
all of the numbers together and divide by the quantity
■ To change a decimal to a percentage, move the
decimal point two units to the right and add a
of numbers in the set.
percentage symbol.
Examples:
Average = qu n a u n m ti b ty er o s f e s t et
.45 = 45% .07 = 7% .9 = 90%
■ To change a percentage to a decimal, simply move
the decimal point two places to the left and elimi-
Find the average of 9, 4, 7, 6, and 4.
+ 6 + 4
nate the percentage symbol.
= 3 5 0 = 6
9 + 4 + 7
5
(because there are 5 numbers in the set)
64% = .64 87% = .87 7% = .07
■ To change a fraction to a percentage, first change
To find the median of a set of numbers, arrange the
the fraction to a decimal. To do this, divide the
numbers in ascending order and find the middle value.
numerator by the denominator. Then change the
decimal to a percentage.
■ If the set contains an odd number of elements,
then simply choose the middle value.
4
5 = .80 = 80% 5 2 = .4 = 40% 1 8 = .125 = 12.5%
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