Minimum Math Skills -

Order of Operations (BEDMAS)

When entering things into a calculator:

Brackets
Exponents (powers)
Division
Multiplication
Addition
Subtraction

Example11.74 + (1.48×0.43)

Do the multiplication first: 1.48 × 0.43 = 0.6364

Then add: 11.74 + 0.6364 = 12.3764

Opposite Operations

Operation	Opposite
+	−
−	+
×	÷
÷	×

Example: x+ 5 = 10

Undo the +5 by subtracting 5: x = 5

Fractions and Decimals

Common conversions

Decimal	Percent
0.50	50%
0.25	25%
0.10	10%
0.07	7%
0.93	93%

Example 0.07 = 7%. Just move the decimal two places.

Finding Percent Left and Right

You'll use this a lot with normal distributions.

Example: 7% is on the right side. What's on the left?

100% − 7% = 93%

or

1.00 − 0.07 = 0.93

This is exactly what happened in the slide you showed me.

Area of a Rectangle

For uniform distributions:

Area = Base × Height

• Base = 0.45

• Height = 1

• 0.45 × 1 = 0.45

Answer = 45%

Area of a Triangle

Meaning of "More Than" and "Less Than"

Symbol	Meaning
>	Greater than
	Less than
≥	Greater than or equal
≤	Less than or equal

Example X > 12

means X is bigger than 12.

Z-Score Formula

Distance on a Number Line

Example

From 3 to 7

• 7 - 3 = 4 The distance is 4.

Any time you need the width of a graph: Width = End - Start

Area = Probability

Area under curve: Probability - Proportion

All mean the same thing.

• Example: Area = 0.45

• means P (X<0.45) = 0.45

• means 45% of observations

Triangle Formula

What does x mean?

"x" simply means: A number that we do not know yet.

• Example: x + 5 = 12

Means what number plus 5 gives 12?

• x = 7