Quantitative Reasoning

(Written with Markdown language.)
## Quantitative Reasoning
### Overall
#### Math describation
##### Arithmetic
* quadrilateral 四边形
* quotient 商，系数
* even integer 偶数
* prime factorization 素因子分解
* prime divisors 素因子
* composite number
* numerator 分子
* denominator 分母
* rational number
* common denominator 公分母
* reciprocal 倒数
* mixed number \(4\frac{3}{4}\)
* base to the exponent power: 3⁵ is read as 3 to the fifth power, 3 is the base, 5 is the exponent.
* square root, cube root, fourth root
* proportion 比例
* base of a percent
* percent change /percent increase /percent decrease
##### Algebra
* like terms: same variables and corresponding variables have the same exponents.
* identity
* how to describe the equations: a quadratic equation in two variables, x and y.
* factor out: 类似于提出公因式吧
* "Two equations with the same variables are called a **system of equations**, and the equations in the sytem are called **simultaneous equations**. "
* The formula of the sultions of quadratic equation is called quadratic formula.
* solution set
* domain of a function
* Coordinate geometry
* parabola
* hyperbola
* vertex
* congruent line segments
* opposite angles = vertical angles
* congruent angles: angles that have equal measures
* corresponding angles 同位角
* acute angle 锐角
* obtuse angle 钝角
* polygons: triangle, quadrilateral, pentagon, hexagon, heptagon, octagon,enneagon/nonagon, decagon
* **equilateral triangle** 等边三角形
* **isoscales trangle** = triangles with at least two congruent sides
* right triangle = a triangle with an interior right angle
* **hypotenuse** = the sideopposite the right angle
* pythagorean theorem 我们所谓的勾股定理
* congruent triangles = same shape and same size
* similar triangles
* square, rectangle, **parallelogram**, **trapezoid** (梯形)
* **chord** = line segment joining two points on the circle.
* **circumference** = distance around a circle
* **sector** = a region bounded by an arc of the circle and two radii.
* **inscribed**, "a polygon inscribed in a circle if all its vertices lie on the circle, or equivalenty, the circle is **circumscribed** about the polygon."
* circumscribed about the circle = each side of the polygon is tangent to the circle./circle is inscribed in the polygon
* concentric circles
* circular cylinder, **lateral surface**, **right circular cylinder**
* **segmented bar graph**
* central tendency: 1. arithmetic mean = average/mean 2. median (n numbers, the middle number or the average of the middle numbers) 3. mode (number occurs most frequently)
* **Positions/locations** (ordered list): 1.basic positions (beginning, middle, end) 2.quartiles (first quartile, second quartile/median, third quartile) 3. percentiles
* range of the numbers = greast - least
* outliers = data value that is unusually small or so unusually large
* **interquartile range** = first quartile - third quartile /measure the spread of the middle half data
* **standard diavation**/population standard deviation 方差
* sample standard deviation : dividing the sum of the squared differences by n-1 instead of n.
* **standardization** = substracting the mean from each value and the dividing the result by the standard deviation
* **In any group of data, most of the data are within about3 standard deviations about or below the mean**
* **intersection** of a set S and antoher set T 交集
* **union** of a set S and another set T 并集
* **disjoint/(mutually exculusive)** = set S and T have no elements in common
* **Venn diagram**
* **inclusion-exclusion principle**
* **permutations of n objects taken k at a time** n的k置换 A^k_n
* **combinations of n objects taken k at a time**
* **sample space** (probability experiment) = the set of all possible outcomes of a random experiment
* random selection/equally likely to be selected
* **mutually exclusive** = can not occur at the same time
* distribution curve/**density curve**/frequency curve
* random variable
* discrete random variables = values consist of discretepoints on a number line
* **normally distributed**
* standard normal distribuation
#### Tips
###### Interest
* Simple interest
* Compound interest