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GRE Math Rules

Subjects : gre, math

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. divisible by 11
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
Number of outcomes yielding E / number of total outcomes
At least two congruent sides; the angles opposite these sides are also congruent
All its interior angles are congruent

2. chord
Sum of its digits is divisible by 3
P(E) + P(F) - P(E and F)
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
Any line connecting two points on a circle. The diameter is a chord

3. dividing fractions
1/x^a
P(E) + P(F) - P(E and F)
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
Invert the second fraction and multiply them

4. area of trapezoid
Three sides congruent - two sides and included angle - two angles and included side
At least two congruent sides; the angles opposite these sides are also congruent
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
Sum of its digits is divisible by 3

5. length of arc of circle
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
At least two congruent sides; the angles opposite these sides are also congruent
A + B - their intersection
All its interior angles are congruent

6. area of parallelogram
All its interior angles are congruent
Last three digits (taken together) are divisible by 8
Base * height
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.

7. possible combinations of three digits without allowing repeats
(n-2)(180 degrees)
Opposite angles formed by two intersecting lines; always congruent
1098 etc
N-2

8. (x^a)(x^b)
P(E and F) = P(E)P(F)
x^(a+b)
(n-2)(180 degrees)
Always equal - i.e. 9 choose 3 = 9 choose 6

9. area of cylinder
N(n-1)(n-2)...(2)(1) = n!
Mean of the two middle ones
1/x^a
2(pir^2) + 2pirh; the two bases and the side

10. (x^a)(y^a)
A + B - their intersection
Opposite angles formed by two intersecting lines; always congruent
(xy)^a
1098 etc

11. sides of 30/60/90 triangle
1 - 2 - root(3); note that this is half of an equilateral triangle
A + B - their intersection
Any line connecting two points on a circle. The diameter is a chord
|S|

12. standardization/normalization
|S|
Always equal - i.e. 9 choose 3 = 9 choose 6
Subtract the mean from each value and divide by the standard deviation
Base * height

13. probability that either E or F occur
|S|
x^ab
N!/(n-k)!
P(E) + P(F) - P(E and F)

14. divisible by 9
Sum of its digits is divisible by 9
A list is ordered and can have duplicates
1098 etc
Less affected by outliers than the mean

15. permutations of n objects taken k at a time (order counts)
Opposite angles formed by two intersecting lines; always congruent
N!/(n-k)!
Pi * r^2
A + B - their intersection

16. sides of isoceles right triangle
1 - 2 - root(3); note that this is half of an equilateral triangle
1 - 1 - root(2)
1
N!/k!(n-k)! which is also denotes as n choose k

17. circumference of circle
101010
The sum of the areas of the six faces: 2(lw + lh + wh)
Base * height
2pi*r

18. regular polygon
Three sides congruent - two sides and included angle - two angles and included side
Number of outcomes yielding E / number of total outcomes
All its interior angles are congruent
Base * height

19. differences between a set and a list
Number of outcomes yielding E / number of total outcomes
A + B - their intersection
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
A list is ordered and can have duplicates

20. combinations of n objects taken k at a time (order doesn'T count)
The sum of the areas of the six faces: 2(lw + lh + wh)
P(E or F) = P(E) + P(F)
x^(a-b) or a/x^(b-a)
N!/k!(n-k)! which is also denotes as n choose k

21. permutations of n different objects
Rules for 2 and three: even and the sum of its digits is divisible by three
(x^a)/(y^a)
N(n-1)(n-2)...(2)(1) = n!
All its interior angles are congruent

22. sum of measures of interior angles of a polygon with n sides
Last three digits (taken together) are divisible by 8
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
(n-2)(180 degrees)
1 - 2 - root(3); note that this is half of an equilateral triangle

23. hypotenuse
Side opposite the right angle
1 - 1 - root(2)
x^(a+b)
Pi * r^2

24. area of sector of circle
1 if decimals - 100 if percents
1
Number of outcomes yielding E / number of total outcomes
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.

25. divisible by 6
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
Rules for 2 and three: even and the sum of its digits is divisible by three

26. how to tell if something is prime
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
Last two digits (taken together) are divisible by 4
In computing the average squared difference from the mean (taking the root of this is the standard deviation) - divide by n-1 instead of n
Invert the second fraction and multiply them

27. divisible by 4
Last two digits (taken together) are divisible by 4
(n-2)(180 degrees)
1 - 1 - root(2)
P(E) + P(F) - P(E and F)

28. number of elements in set S
Last two digits (taken together) are divisible by 4
(x^a)/(y^a)
|S|
In computing the average squared difference from the mean (taking the root of this is the standard deviation) - divide by n-1 instead of n

29. advantage of median
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
Three sides congruent - two sides and included angle - two angles and included side
Less affected by outliers than the mean
x^ab

30. what'S the median if there are an even number of data points?
P(E) + P(F) - P(E and F)
Mean of the two middle ones
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
1

31. congruency of triangles
N(n-1)(n-2)...(2)(1) = n!
A list is ordered and can have duplicates
Three sides congruent - two sides and included angle - two angles and included side
Last three digits (taken together) are divisible by 8

32. volume of rectangle
Lwh
2pi*r
1
(x^a)/(y^a)

33. x^0
Rules for 2 and three: even and the sum of its digits is divisible by three
2(pir^2) + 2pirh; the two bases and the side
1
1 if decimals - 100 if percents

34. sum of relative frequencies in a frequency distribution
Any line connecting two points on a circle. The diameter is a chord
1/x^a
Subtract the mean from each value and divide by the standard deviation
1 if decimals - 100 if percents

35. divisible by 8
Last two digits (taken together) are divisible by 4
1098 etc
(n-2)(180 degrees)
Last three digits (taken together) are divisible by 8

36. possible combinations of three digits allowing repeats
2(pir^2) + 2pirh; the two bases and the side
1098 etc
101010
N!/(n-k)!

37. probability of an event E
A + B - their intersection
Number of outcomes yielding E / number of total outcomes
101010
Subtract the mean from each value and divide by the standard deviation

38. relationship between n choose k and n choose n-k
Any line connecting two points on a circle. The diameter is a chord
Always equal - i.e. 9 choose 3 = 9 choose 6
Pi*r^2h
1 if decimals - 100 if percents

39. area of rectangle
Subtract the mean from each value and divide by the standard deviation
Last three digits (taken together) are divisible by 8
The sum of the areas of the six faces: 2(lw + lh + wh)
2pi*r

40. similar triangles
1 - 1 - root(2)
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
Number of outcomes yielding E / number of total outcomes
Sum of its digits is divisible by 9

41. volume of cylinder
Pi*r^2h
P(E and F) = P(E)P(F)
Base * height
x^(a-b) or a/x^(b-a)

42. area of circle
N!/k!(n-k)! which is also denotes as n choose k
(n-2)(180 degrees)
Pi * r^2
Base * height

43. difference between normal or population standard deviation and the sample standard deviation
Rules for 2 and three: even and the sum of its digits is divisible by three
1 if decimals - 100 if percents
In computing the average squared difference from the mean (taking the root of this is the standard deviation) - divide by n-1 instead of n
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.

44. independence of two events E and F
(n-2)(180 degrees)
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
P(E and F) = P(E)P(F)
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.

45. x^-a
All its interior angles are congruent
The sum of the areas of the six faces: 2(lw + lh + wh)
Always equal - i.e. 9 choose 3 = 9 choose 6
1/x^a

46. isosceles triangle
At least two congruent sides; the angles opposite these sides are also congruent
Subtract the mean from each value and divide by the standard deviation
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
x^(a-b) or a/x^(b-a)

47. vertical angles
Opposite angles formed by two intersecting lines; always congruent
x^ab
1/2 base * height
Pi * r^2

48. (x/y)^a
1098 etc
Pi*r^2h
1
(x^a)/(y^a)

49. union of sets A and B
1 if decimals - 100 if percents
Invert the second fraction and multiply them
A + B - their intersection
Side opposite the right angle

50. (x^a)^b
Lwh
x^ab
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
Number of outcomes yielding E / number of total outcomes