Thursday, June 23, 2011

test latex embedding...

When \(a \ne 0\), there are two solutions to \(ax^2 + bx + c = 0\) and they are $$x = {-b \pm \sqrt{b^2-4ac} \over 2a}.$$
  • a ratio is the comparison of two numbers that can be expressed as quotient $$a:b = \frac{a}{b}$$

Ratios, rates, proportion and odds

  • ratios
    • a ratio is the comparison of two numbers that can be expressed as quotient $$a:b \rightarrow \frac{a}{b}$$
    • rate
      • a rate is a type of ratio, expressed as a quotient, comparing the change in one value (numerator) per change in another value (denominator): $$\Delta a:\Delta b \rightarrow \frac{\Delta a}{\Delta b} $$
      • example: death rate, calculate as the number of deaths divided by the person time at risk
    • proportion
      • a proportion is a type of ratio, expressed as a quotient, comparing a part (numerator) to the whole (denominator): $$ a:(a+b) \rightarrow \frac{a}{a+b}$$
    • odds
      • is a type of ratio, expressed as quotient, comparing a part (numerator) to the remainder (denominator): $$c:d \rightarrow \frac{c}{d}$$

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