Equations
| Terms | Def/Formula |
|---|---|
| Average | average = sum of terms/number of terms |
| Average speed | average speed = total distance/total time |
| Sum | sum = average × (number of terms) |
| Mode | mode = value in the list that appears most often |
| Median | median = middle value in the list (which must be sorted) Example: median of {3, 10, 9, 27, 50} = 10 Example: median of {3, 9, 10, 27} = (9 + 10)/2 = 9.5 |
| Probability | probability = number of desired outcomes/number of total outcomes |
| Integers | . . . , -3, -2, -1, 0, 1, 2, 3, . . . |
| Rationals | fractions, that is, anything expressable as a ratio of integers |
| Reals | integers plus rationals plus special numbers such as √ 2, √ 3 and π |
Arithmetic Sequences
- each term is equal to the previous term plus d
- Sequence: t1, t1 + d, t1 + 2d, . . .
- Example: d = 4 and t1 = 3 gives the sequence 3, 7, 11, 15, . . .
Geometric Sequences
- each term is equal to the previous term times r
- Sequence: t1, t1 · r, t1 · r2, . . .
- Example: r = 2 and t1 = 3 gives the sequence 3, 6, 12, 24, . . .
Order Of Operations
- PEMDAS
(Parentheses / Exponents / Multiply / Divide / Add / Subtract)
Factors
- the factors of a number divide into that number without a remainder
- Example: the factors of 52 are 1, 2, 4, 13, 26, and 52
Multiples
- the multiples of a number are divisible by that number without a remainder
- Example: the positive multiples of 20 are 20, 40, 60, 80, . . .
Percents
- use the following formula to find part, whole, or percent
- part = percent/100 × whole
Free resources for SAT Math
SAT Math Quiz 1
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