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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. circumference of circle
Any line connecting two points on a circle. The diameter is a chord
101010
Last two digits (taken together) are divisible by 4
2pi*r

2. (x^a)(y^a)
x^(a+b)
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
Three sides congruent - two sides and included angle - two angles and included side
(xy)^a

3. area of parallelogram
Base * height
Sum of its digits is divisible by 3
Less affected by outliers than the mean
A + B - their intersection

4. volume of rectangle
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
(xy)^a
Lwh
101010

5. area of a non-right triangle
(n-2)(180 degrees)
Always equal - i.e. 9 choose 3 = 9 choose 6
Pi*r^2h
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.

6. sum of measures of interior angles of a polygon with n sides
Pi * r^2
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
Three sides congruent - two sides and included angle - two angles and included side
(n-2)(180 degrees)

7. advantage of median
1/2 base * height
Mean of the two middle ones
Sum of its digits is divisible by 9
Less affected by outliers than the mean

8. divisible by 8
Last three digits (taken together) are divisible by 8
N(n-1)(n-2)...(2)(1) = n!
Always equal - i.e. 9 choose 3 = 9 choose 6
All its interior angles are congruent

9. mutually exclusive
Mean of the two middle ones
Pi*r^2h
Invert the second fraction and multiply them
P(E or F) = P(E) + P(F)

10. combinations of n objects taken k at a time (order doesn'T count)
1 - 1 - root(2)
Rules for 2 and three: even and the sum of its digits is divisible by three
N!/k!(n-k)! which is also denotes as n choose k
The sum of the areas of the six faces: 2(lw + lh + wh)

11. union of sets A and B
Pi * r^2
101010
A + B - their intersection
A list is ordered and can have duplicates

12. independence of two events E and F
Base * height
N!/k!(n-k)! which is also denotes as n choose k
P(E and F) = P(E)P(F)
1098 etc

13. volume of cylinder
x^ab
Number of outcomes yielding E / number of total outcomes
1 if decimals - 100 if percents
Pi*r^2h

14. (x^a)^b
Sum of its digits is divisible by 3
x^ab
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

15. congruency of triangles
1/x^a
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
Any line connecting two points on a circle. The diameter is a chord

16. permutations of n different objects
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
x^(a+b)
1098 etc
N(n-1)(n-2)...(2)(1) = n!

17. possible combinations of three digits without allowing repeats
N(n-1)(n-2)...(2)(1) = n!
1098 etc
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
1/x^a

18. divisible by 3
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
1
1 - 2 - root(3); note that this is half of an equilateral triangle
Sum of its digits is divisible by 3

19. area of circle
Subtract the mean from each value and divide by the standard deviation
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
Pi * r^2
Sum of its digits is divisible by 9

20. length of arc of circle
Last three digits (taken together) are divisible by 8
Always equal - i.e. 9 choose 3 = 9 choose 6
Base * height
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.

21. area of cylinder
2(pir^2) + 2pirh; the two bases and the side
Lwh
(x^a)/(y^a)
Last three digits (taken together) are divisible by 8

22. sum of relative frequencies in a frequency distribution
1 if decimals - 100 if percents
A + B - their intersection
2pi*r
1 - 2 - root(3); note that this is half of an equilateral triangle

23. divisible by 11
1
N-2
1 if decimals - 100 if percents
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.

24. standardization/normalization
1 if decimals - 100 if percents
Subtract the mean from each value and divide by the standard deviation
|S|
Always equal - i.e. 9 choose 3 = 9 choose 6

25. permutations of n objects taken k at a time (order counts)
2(pir^2) + 2pirh; the two bases and the side
Pi * r^2
N!/(n-k)!
1 - 2 - root(3); note that this is half of an equilateral triangle

26. area of trapezoid
A list is ordered and can have duplicates
1 - 2 - root(3); note that this is half of an equilateral triangle
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
The sum of the areas of the six faces: 2(lw + lh + wh)

27. regular polygon
Invert the second fraction and multiply them
101010
All its interior angles are congruent
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

28. differences between a set and a list
Last two digits (taken together) are divisible by 4
Sum of its digits is divisible by 3
(xy)^a
A list is ordered and can have duplicates

29. chord
Any line connecting two points on a circle. The diameter is a chord
(xy)^a
Mean of the two middle ones
N-2

30. divisible by 4
Last two digits (taken together) are divisible by 4
x^(a-b) or a/x^(b-a)
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
1 - 1 - root(2)

31. number of elements in set S
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
x^(a+b)
|S|
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication

32. (x^a)/(x^b)
A + B - their intersection
N-2
A list is ordered and can have duplicates
x^(a-b) or a/x^(b-a)

33. x^0
1
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
101010
2(pir^2) + 2pirh; the two bases and the side

34. divisible by 9
Sum of its digits is divisible by 9
Any line connecting two points on a circle. The diameter is a chord
Lwh
1 - 1 - root(2)

35. isosceles triangle
1/2 base * height
At least two congruent sides; the angles opposite these sides are also congruent
Always equal - i.e. 9 choose 3 = 9 choose 6
A list is ordered and can have duplicates

36. probability that either E or F occur
1/2 base * height
Any line connecting two points on a circle. The diameter is a chord
P(E) + P(F) - P(E and F)
Lwh

37. probability of an event E
x^(a+b)
Number of outcomes yielding E / number of total outcomes
Mean of the two middle ones
Rules for 2 and three: even and the sum of its digits is divisible by three

38. how many triangles can a polygon of n sides be divided into?
1 - 2 - root(3); note that this is half of an equilateral triangle
N-2
Mean of the two middle ones
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.

39. (x^a)(x^b)
1 - 2 - root(3); note that this is half of an equilateral triangle
x^(a+b)
Number of outcomes yielding E / number of total outcomes
Pi*r^2h

40. hypotenuse
Any line connecting two points on a circle. The diameter is a chord
Side opposite the right angle
A list is ordered and can have duplicates
(n-2)(180 degrees)

41. divisible by 6
Rules for 2 and three: even and the sum of its digits is divisible by three
A + B - their intersection
Always equal - i.e. 9 choose 3 = 9 choose 6
Last two digits (taken together) are divisible by 4

42. relationship between n choose k and n choose n-k
Always equal - i.e. 9 choose 3 = 9 choose 6
2pi*r
A list is ordered and can have duplicates
The sum of the areas of the six faces: 2(lw + lh + wh)

43. area of triangle
Three sides congruent - two sides and included angle - two angles and included side
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
1/2 base * height
(n-2)(180 degrees)

44. similar triangles
Rules for 2 and three: even and the sum of its digits is divisible by three
101010
Sum of its digits is divisible by 3
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication

45. what'S the median if there are an even number of data points?
1 - 1 - root(2)
Opposite angles formed by two intersecting lines; always congruent
N!/(n-k)!
Mean of the two middle ones

46. vertical angles
All its interior angles are congruent
Base * height
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
Opposite angles formed by two intersecting lines; always congruent

47. sides of isoceles right triangle
1 - 2 - root(3); note that this is half of an equilateral triangle
1 - 1 - root(2)
N!/k!(n-k)! which is also denotes as n choose k
All its interior angles are congruent

48. sides of 30/60/90 triangle
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
1 - 2 - root(3); note that this is half of an equilateral triangle
Pi*r^2h
101010

49. (x/y)^a
x^(a-b) or a/x^(b-a)
(x^a)/(y^a)
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

50. difference between normal or population standard deviation and the sample standard deviation
|S|
Opposite angles formed by two intersecting lines; always congruent
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
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides