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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. relationship between n choose k and n choose n-k
Base * height
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
P(E or F) = P(E) + P(F)
Always equal - i.e. 9 choose 3 = 9 choose 6

2. permutations of n different objects
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
1 if decimals - 100 if percents
N(n-1)(n-2)...(2)(1) = n!
Any line connecting two points on a circle. The diameter is a chord

3. area of triangle
1/2 base * height
1098 etc
All its interior angles are congruent
The sum of the areas of the six faces: 2(lw + lh + wh)

4. sides of isoceles right triangle
Opposite angles formed by two intersecting lines; always congruent
P(E and F) = P(E)P(F)
Lwh
1 - 1 - root(2)

5. probability that either E or F occur
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
(xy)^a
N!/(n-k)!
P(E) + P(F) - P(E and F)

6. union of sets A and B
A + B - their intersection
Last three digits (taken together) are divisible by 8
Pi * r^2
(x^a)/(y^a)

7. divisible by 11
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
x^(a+b)
x^(a-b) or a/x^(b-a)

8. regular polygon
Sum of its digits is divisible by 3
All its interior angles are congruent
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).

9. possible combinations of three digits allowing repeats
Any line connecting two points on a circle. The diameter is a chord
101010
N(n-1)(n-2)...(2)(1) = n!
A list is ordered and can have duplicates

10. area of rectangle
Last three digits (taken together) are divisible by 8
Invert the second fraction and multiply them
Last two digits (taken together) are divisible by 4
The sum of the areas of the six faces: 2(lw + lh + wh)

11. area of cylinder
Less affected by outliers than the mean
Pi*r^2h
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
2(pir^2) + 2pirh; the two bases and the side

12. dividing fractions
Invert the second fraction and multiply them
Lwh
|S|
P(E or F) = P(E) + P(F)

13. chord
Opposite angles formed by two intersecting lines; always congruent
Any line connecting two points on a circle. The diameter is a chord
1/2 base * height
|S|

14. x^-a
Base * height
1/x^a
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
(x^a)/(y^a)

15. what'S the median if there are an even number of data points?
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.
x^(a-b) or a/x^(b-a)
Any line connecting two points on a circle. The diameter is a chord

16. vertical angles
1
Opposite angles formed by two intersecting lines; always congruent
A list is ordered and can have duplicates
Last two digits (taken together) are divisible by 4

17. advantage of median
2pi*r
A list is ordered and can have duplicates
1 - 1 - root(2)
Less affected by outliers than the mean

18. standardization/normalization
Number of outcomes yielding E / number of total outcomes
Subtract the mean from each value and divide by the standard deviation
(x^a)/(y^a)
Lwh

19. area of parallelogram
Base * height
1 if decimals - 100 if percents
x^(a-b) or a/x^(b-a)
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.

20. volume of rectangle
Base * height
Lwh
1 - 1 - root(2)
Number of outcomes yielding E / number of total outcomes

21. divisible by 3
x^ab
Subtract the mean from each value and divide by the standard deviation
Sum of its digits is divisible by 3
P(E) + P(F) - P(E and F)

22. sum of measures of interior angles of a polygon with n sides
(n-2)(180 degrees)
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
Number of outcomes yielding E / number of total outcomes

23. circumference of circle
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
Last three digits (taken together) are divisible by 8
P(E) + P(F) - P(E and F)
2pi*r

24. area of trapezoid
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
Invert the second fraction and multiply them
Sum of its digits is divisible by 9

25. (x^a)(x^b)
Mean of the two middle ones
x^(a+b)
1 - 2 - root(3); note that this is half of an equilateral triangle
2pi*r

26. combinations of n objects taken k at a time (order doesn'T count)
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
N!/k!(n-k)! which is also denotes as n choose k
All its interior angles are congruent
P(E) + P(F) - P(E and F)

27. sides of 30/60/90 triangle
Last three digits (taken together) are divisible by 8
Lwh
Always equal - i.e. 9 choose 3 = 9 choose 6
1 - 2 - root(3); note that this is half of an equilateral triangle

28. possible combinations of three digits without allowing repeats
Less affected by outliers than the mean
2(pir^2) + 2pirh; the two bases and the side
1098 etc
Pi * r^2

29. area of sector of circle
N!/k!(n-k)! which is also denotes as n choose k
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
A + B - their intersection
P(E and F) = P(E)P(F)

30. how to tell if something is prime
Any line connecting two points on a circle. The diameter is a chord
2(pir^2) + 2pirh; the two bases and the side
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
x^(a-b) or a/x^(b-a)

31. divisible by 4
(xy)^a
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
Last two digits (taken together) are divisible by 4
Subtract the mean from each value and divide by the standard deviation

32. length of arc of circle
N!/(n-k)!
2(pir^2) + 2pirh; the two bases and the side
Last three digits (taken together) are divisible by 8
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.

33. differences between a set and a list
A list is ordered and can have duplicates
Mean of the two middle ones
1 - 2 - root(3); note that this is half of an equilateral triangle
Opposite angles formed by two intersecting lines; always congruent

34. divisible by 8
Last three digits (taken together) are divisible by 8
2(pir^2) + 2pirh; the two bases and the side
N-2
N!/k!(n-k)! which is also denotes as n choose k

35. mutually exclusive
All its interior angles are congruent
x^ab
Side opposite the right angle
P(E or F) = P(E) + P(F)

36. divisible by 6
N-2
1
Rules for 2 and three: even and the sum of its digits is divisible by three
A list is ordered and can have duplicates

37. sum of relative frequencies in a frequency distribution
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
1 if decimals - 100 if percents
(xy)^a
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.

38. area of a non-right triangle
A + B - their intersection
Pi * r^2
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
P(E or F) = P(E) + P(F)

39. (x^a)/(x^b)
Sum of its digits is divisible by 9
x^(a-b) or a/x^(b-a)
1/2 base * height
N(n-1)(n-2)...(2)(1) = n!

40. number of elements in set S
N-2
All its interior angles are congruent
N(n-1)(n-2)...(2)(1) = n!
|S|

41. permutations of n objects taken k at a time (order counts)
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
N!/(n-k)!
1/2 base * height
x^(a+b)

42. how many triangles can a polygon of n sides be divided into?
The sum of the areas of the six faces: 2(lw + lh + wh)
1 - 1 - root(2)
N-2
Last two digits (taken together) are divisible by 4

43. volume of cylinder
1098 etc
Pi*r^2h
2(pir^2) + 2pirh; the two bases and the side
Number of outcomes yielding E / number of total outcomes

44. (x^a)(y^a)
x^(a-b) or a/x^(b-a)
Sum of its digits is divisible by 3
(xy)^a
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.

45. difference between normal or population standard deviation and the sample standard deviation
|S|
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
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
2(pir^2) + 2pirh; the two bases and the side

46. area of circle
2pi*r
Pi * r^2
Invert the second fraction and multiply them
Pi*r^2h

47. independence of two events E and F
Last three digits (taken together) are divisible by 8
Less affected by outliers than the mean
P(E and F) = P(E)P(F)
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).

48. congruency of triangles
P(E) + P(F) - P(E and F)
(x^a)/(y^a)
Three sides congruent - two sides and included angle - two angles and included side
x^ab

49. (x/y)^a
1
1/2 base * height
Number of outcomes yielding E / number of total outcomes
(x^a)/(y^a)

50. (x^a)^b
Last two digits (taken together) are divisible by 4
Pi*r^2h
x^ab
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.