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32 Cards in this Set
- Front
- Back
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Fractions:
Add or subtract Multiply Divide |
common denominator first
multiply across flip the 2nd fraction, multiply |
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Prime numbers are
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#s that can only be divided by itself and 1
Ex: 2, 3, 5, 7, 11, 13, 17, 19, 23,... |
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Mode is
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most repeated #
Ex: -2, 3, 7, 1, 7, 4, 8 Answer: 7 |
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Median is
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middle # in proper order
Ex:1, 2, 4, 7, 8 Answer: 4 Ex: 1, 2, 3, 5, 7, 8 Answer: 4 (add 2 middle #s then / by 2) |
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Average is calculated by
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add up #s / how many #s
OR add up #s=avg*how many #s Ex: 5 tests Avg: 94 6 tests Avg: 89 How many testers for each? Answer: 470 & 534 |
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Exponents:
x^3*x^4 (x^3)^4 x^6/x^2 x^0 3^-2 |
x^7
x^12 x^4 1 1/3^2 |
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Positive or Negative Slope?
\ (downward L to R) / (upward L to R) |
Negative slope
Positive slope |
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Ratios:
8 to 9 |
8/9
OR 8:9 |
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% increase & decrease
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difference in %/where you start
Ex: 2010 40% 2011 60% Increased? Answer: 20/40=50% Ex: 2010 60% 2011 40% Decreased? Answer: 20/60=33.33% |
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Order of Operations:
L to R parentheses exponents multiply & divide add & subtract |
Ex: 8+3-6+5=? Answer: 10
Ex: -4^2=? Answer: -16 Ex: (-4)^2=? Answer: 16 |
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When increasing a percentage, then decreasing the same percentage, you will always lose value. Larger %, larger loss.
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Ex: Increase 10% per 100, then decide to decrease by 10%.
Answer: Increased to 110, then decreased by 11. Now 99 not 100!! |
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Standard Deviations:
closer numbers? further numbers? |
smaller SD
larger SD |
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How long to paint a house together if, by themselves, takes Bob 5 days and Mary 3 days?
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Answer: 1 and 7/8 days
1. Flip 1/5 & 1/3 2. Add 1/5+1/3=8/15 3. Flip 15/8 days |
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Slope:
y-axis: undefined x-axis: zero |
Slope Equations:
y=mx+b (m=slope) slope=rise/run (y/x) y2-y1/x2-x1 |
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Circles:
Parameter? Area? Volume? |
C=pie*d OR pie*2*r
A=pie*r^2 V=base*height*depth |
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Squares/Rectangles:
Parameter? Area? Volume? |
P=add all sides together
A=length*width V=base*height*depth |
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Triangles:
Parameter? Area? Volume? |
P=add sides together
A=1/2 of length*width V=base*height*depth |
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Square has diagonal line of 8. What is the area?
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Answer: 32
D^2/2 (64/2=32) |
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Circles are perfectly proportioned. Think of circles for problems regarding clocks.
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each min is 6 degrees, every 5 min is 30 degrees. Calculate using minute hand first, then hour hand.
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How many times do the hands of a clock form a 90 degree angle in a 12 hour period?
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Answer: 22 times
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Triangles:
sum of 2 sides MUST be larger than 3rd side! |
Angles and sides go together. Sum of the three angles=180 degrees.
Remember that a triangle is half of a square: D^2/2 |
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Right triangle with two equal sides of x, the third side will be x*sq. root of 2.
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Right triangle with angles 30, 60 & 90, sides are x, 2*x, x*sq. root of 3, 2*x, respectively.
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Parallel lines with a line through it has equal angles in the same quadrants.
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UL=UL and so on.
*Illustrated in GRE class 1 notes |
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Shortcut for a^2+b^2=c^2:
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Sides with: 3x, 4x, 5x
Common triangle: Sides with: 5x, 12x, 13x |
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Hexagons:
Has six equal triangles. (# of sides-2)*180 |
Area of hexagon:
1/2side)^2*sq. root of 3 Must have sq. root of 3 in the answer!! |
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Octagons:
Equal angular: flat sides are 1, slanted sides are sq. root of 2. Area: 7*(flat sides)^2 |
Area (regular): 8(1/2side)^2+8(1/2side)^2*sq. root of 2
Answer: 128*sq. root of 2+128 |
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Quantitative Comparison Rules:
1. answer choices always same: A>B then answer A A<B then answer B A=B then answer C Need more info then answer D 2. answer never D if #s involved 3. answers A, B, C must be true for ALL possibilities 4. if conflict arises, answer D 5. Do not assume!! |
Quantitative Comparison Strategies:
1. try FIVE #s (except exponents) 0, 1, 2, -1, 1/2 2. Equate A & B 3. if choice between question & #s, try the # first 4. Draw diagrams 5. Look for patterns |
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Multiple Choice Strategies:
1. use answer choices when #s and work problem backwards 2. draw a diagram 3. eliminate stupid answers 4. if variables in problem and answers, pick #s and solve STARTING with C, choose same answer 5. look for patterns |
Hints: no such thing as half cents.
Also don't use 1 as a # for variables, try 2 instead. |
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y=f(x)
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Ex: ETS pg. 152 #7
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Triangle with angles 90, 45, 45 have these sides:
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sq. root of 2, sq. root of 2, 2
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Triangle with angles 90, 60, 30 have these sides, respectively:
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2, sq. root of 3, 1
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Remember:
Use answer choices for age problems and work backwards. |
Short-cut Hint:
120A=80B Plug in 80 for A & 120 for B 120*80=80*120 |
