Math Concepts Review - Page 2
Translating words to expressions:
Word Phrase
Expression
Comment
three times a number
3 x
A number next to a variable means multiply
half of a number
x / 2 or
½ x
"half of", "third of", "one fifth of" all mean multiply by fractions
one minus 3 times a number
1 - 3 x
one
less than
3 times a number
3 x - 1
Tricky! "less than" means subtract from what follows the "less than"
a number
increased
by 5
x + 5
The word "increase" means add
a number
decreased
by 8
x - 8
The word "decrease" means subtract
8
more than
5 times a number
5 x + 8
"more than" means add
6
less than
3 times a number
3 x - 6
"less than" means subtract from what follows the "less than"
Statistics:
Mean
Mode
Median
Range
Mean means average: The average of {3,8,4} is:
(3+8+4)/3 = 5
Mode means the most common: The mode of
{2, 3, 3, 8} is 3
Median is the one in the middle. The median of
{2,8,5,4,1} is 4
(crossing off the highest and lowest)
The range is the highest - the lowest. The range of
{2, 8, 5, 4, 1} is 8 - 1 = 7
Probability:
Example
Problem
Answer
1
What is the probability of
a flipped coin turning up heads?
because there is 1 head
and the coin has 2 sides.
2
What is the probability of pulling the ace of spades out of a deck of 52 cards?
because there is only 1 ace of spades and there are 52 cards.
3
What is the probability of drawing
any ace out of a deck of 52 cards?
because there are 4 aces
in a deck of 52 cards.
4
What is the probability of drawing a red marble out of a bag containing 2 red marbles and 5 blue marbles?
because there are 2 red marbles and 7 marbles in all.
because there is 1 head
because there is only 1 ace of
spades
and there are 52 cards.
because there are 4 aces
because there are 2 red
marbles and 7 marbles in all.