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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. x^0
2(pir^2) + 2pirh; the two bases and the side
1
Rules for 2 and three: even and the sum of its digits is divisible by three
1 - 2 - root(3); note that this is half of an equilateral triangle

2. number of elements in set S
|S|
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
1/x^a
Side opposite the right angle

3. area of cylinder
Sum of its digits is divisible by 9
Always equal - i.e. 9 choose 3 = 9 choose 6
P(E) + P(F) - P(E and F)
2(pir^2) + 2pirh; the two bases and the side

4. differences between a set and a list
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
x^(a+b)
Last two digits (taken together) are divisible by 4
A list is ordered and can have duplicates

5. length of arc of circle
Three sides congruent - two sides and included angle - two angles and included side
Always equal - i.e. 9 choose 3 = 9 choose 6
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
Lwh

6. area of trapezoid
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
N!/k!(n-k)! which is also denotes as n choose k
Less affected by outliers than the mean
Any line connecting two points on a circle. The diameter is a chord

7. area of sector of circle
Sum of its digits is divisible by 9
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
N!/(n-k)!
(x^a)/(y^a)

8. what'S the median if there are an even number of data points?
Side opposite the right angle
Mean of the two middle ones
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
1

9. regular polygon
All its interior angles are congruent
Three sides congruent - two sides and included angle - two angles and included side
Last three digits (taken together) are divisible by 8
N!/(n-k)!

10. vertical angles
x^ab
Opposite angles formed by two intersecting lines; always congruent
P(E or F) = P(E) + P(F)
1/x^a

11. congruency of triangles
Three sides congruent - two sides and included angle - two angles and included side
Any line connecting two points on a circle. The diameter is a chord
(n-2)(180 degrees)
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.

12. divisible by 3
2(pir^2) + 2pirh; the two bases and the side
N!/(n-k)!
(n-2)(180 degrees)
Sum of its digits is divisible by 3

13. area of triangle
P(E) + P(F) - P(E and F)
Side opposite the right angle
Mean of the two middle ones
1/2 base * height

14. area of parallelogram
x^(a+b)
Base * height
Subtract the mean from each value and divide by the standard deviation
Sum of its digits is divisible by 3

15. area of a non-right triangle
A list is ordered and can have duplicates
(n-2)(180 degrees)
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.

16. union of sets A and B
Pi * r^2
N!/k!(n-k)! which is also denotes as n choose k
Number of outcomes yielding E / number of total outcomes
A + B - their intersection

17. independence of two events E and F
P(E and F) = P(E)P(F)
Side opposite the right angle
(x^a)/(y^a)
Last two digits (taken together) are divisible by 4

18. probability that either E or F occur
Last three digits (taken together) are divisible by 8
P(E) + P(F) - P(E and F)
(x^a)/(y^a)
1 if decimals - 100 if percents

19. 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).
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
Opposite angles formed by two intersecting lines; always congruent

20. (x^a)^b
The sum of the areas of the six faces: 2(lw + lh + wh)
x^ab
Pi*r^2h
Opposite angles formed by two intersecting lines; always congruent

21. similar triangles
N-2
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
N(n-1)(n-2)...(2)(1) = n!
Opposite angles formed by two intersecting lines; always congruent

22. (x/y)^a
All its interior angles are congruent
(x^a)/(y^a)
A list is ordered and can have duplicates
Base * height

23. isosceles triangle
1/2 base * height
At least two congruent sides; the angles opposite these sides are also congruent
2pi*r
Opposite angles formed by two intersecting lines; always congruent

24. hypotenuse
2pi*r
(xy)^a
Side opposite the right angle
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides

25. area of circle
N-2
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
Pi * r^2
1

26. circumference of circle
2pi*r
Sum of its digits is divisible by 9
Pi * r^2
(xy)^a

27. possible combinations of three digits without allowing repeats
1098 etc
Less affected by outliers than the mean
2pi*r
1

28. sum of relative frequencies in a frequency distribution
1 if decimals - 100 if percents
1/2 base * height
A + B - their intersection
N!/(n-k)!

29. possible combinations of three digits allowing repeats
N-2
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
|S|
101010

30. (x^a)(x^b)
Subtract the mean from each value and divide by the standard deviation
Rules for 2 and three: even and the sum of its digits is divisible by three
x^(a+b)
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides

31. sum of measures of interior angles of a polygon with n sides
Rules for 2 and three: even and the sum of its digits is divisible by three
x^ab
Opposite angles formed by two intersecting lines; always congruent
(n-2)(180 degrees)

32. how many triangles can a polygon of n sides be divided into?
N-2
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
x^ab
x^(a-b) or a/x^(b-a)

33. 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)
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
N!/k!(n-k)! which is also denotes as n choose k
1 - 2 - root(3); note that this is half of an equilateral triangle

34. volume of cylinder
Sum of its digits is divisible by 9
Sum of its digits is divisible by 3
Pi*r^2h
1/x^a

35. sides of 30/60/90 triangle
Last two digits (taken together) are divisible by 4
1 - 2 - root(3); note that this is half of an equilateral triangle
101010
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication

36. relationship between n choose k and n choose n-k
1/x^a
|S|
Number of outcomes yielding E / number of total outcomes
Always equal - i.e. 9 choose 3 = 9 choose 6

37. divisible by 11
Rules for 2 and three: even and the sum of its digits is divisible by three
At least two congruent sides; the angles opposite these sides are also congruent
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
2pi*r

38. probability of an event E
Last two digits (taken together) are divisible by 4
Pi * r^2
Number of outcomes yielding E / number of total outcomes
2pi*r

39. (x^a)/(x^b)
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-b) or a/x^(b-a)
1 if decimals - 100 if percents

40. divisible by 8
Last three digits (taken together) are divisible by 8
2(pir^2) + 2pirh; the two bases and the side
Three sides congruent - two sides and included angle - two angles and included side
A + B - their intersection

41. standardization/normalization
Three sides congruent - two sides and included angle - two angles and included side
Mean of the two middle ones
Subtract the mean from each value and divide by the standard deviation
1 - 1 - root(2)

42. advantage of median
Less affected by outliers than the mean
Subtract the mean from each value and divide by the standard deviation
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.

43. mutually exclusive
The sum of the areas of the six faces: 2(lw + lh + wh)
Always equal - i.e. 9 choose 3 = 9 choose 6
101010
P(E or F) = P(E) + P(F)

44. difference between normal or population standard deviation and the sample standard deviation
Sum of its digits is divisible by 9
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
N!/(n-k)!
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.

45. dividing fractions
Invert the second fraction and multiply them
1 if decimals - 100 if percents
N!/k!(n-k)! which is also denotes as n choose k
Side opposite the right angle

46. area of rectangle
|S|
P(E) + P(F) - P(E and F)
The sum of the areas of the six faces: 2(lw + lh + wh)
N-2

47. volume of rectangle
2(pir^2) + 2pirh; the two bases and the side
A + B - their intersection
Pi*r^2h
Lwh

48. permutations of n objects taken k at a time (order counts)
Three sides congruent - two sides and included angle - two angles and included side
N!/(n-k)!
All its interior angles are congruent
Always equal - i.e. 9 choose 3 = 9 choose 6

49. permutations of n different objects
1098 etc
N(n-1)(n-2)...(2)(1) = n!
1
1/2 base * height

50. (x^a)(y^a)
(xy)^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
Pi*r^2h
2(pir^2) + 2pirh; the two bases and the side