GRE Formulas
Terms
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 Formula for % increase

*  Formula for % decrease

Where X=the base 
What does this equal? 
answer 
What does this equal 
answer  x^22xy+y^2=
 (xy)^2
 sales price =
 (original price)  (%discount)(original price)
 total price
 (#of items) cost
 Distance
 Rate x time
 30:60:90 triangle
 1:2:square rt of 3
 45:45:90 triangle leg ratios
 1:sr of 2
 Pi =
 approx 3
 nCk
 n! / k!(nk)!
 Av Speed =
 TD / TT
 P(AorB)
 P(A)+P(B)P(A&B)
 W/ probab how do you handle exclusions?
 Divide factorial of # of events y the product of the exclusions
 10% of 30%
 .10x.30
 Volume of Rectangle Solid
 LxWxH
 Sum of terms =
 Average x # of terms
 Slope =

Rise / run
y2y1 / x2x1
neg slope = \
pos slope /  STD =

Avg of array (find mean)
diff btwn each & mean
Square differences
Find mean of squared differences  Probability formula
 # favorable outcomes / # possible outcomes
 6C2
 15
 4C2
 4
 16C4 =
 16C12 =
 multiple of 3
 sum of digits is multiple of 3
 multiple of 4
 last two digits is a multiple of 4
 multiple of 6
 sum of digits is a multiple of 3 and last digit even
 multiple of 9
 sum of digits is a multiple of 3 and sum of last two digits are multiple of 4 ie 135
 % formula =
 part = percent x whole
 Percent increase =
 amount of increase / original whole then x 100
 Percent decrease =
 amount of decrease / original whole then x 100
 What is the average formula

avg = sum / # of terms
sum = avg x # of terms  Avg of evenly spaced #s
 avg of min + max
 How do you count consecutive numbers?
 Max  Min +1
 Ratio formula
 ratio = of / to