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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. standardization/normalization
A list is ordered and can have duplicates
P(E or F) = P(E) + P(F)
1 - 1 - root(2)
Subtract the mean from each value and divide by the standard deviation

2. area of rectangle
Last two digits (taken together) are divisible by 4
All its interior angles are congruent
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
The sum of the areas of the six faces: 2(lw + lh + wh)

3. area of trapezoid
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
Number of outcomes yielding E / number of total outcomes
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
A + B - their intersection

4. area of sector of circle
Side opposite the right angle
1 - 1 - root(2)
P(E or F) = P(E) + P(F)
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.

5. mutually exclusive
P(E or F) = P(E) + P(F)
N!/(n-k)!
(n-2)(180 degrees)
Number of outcomes yielding E / number of total outcomes

6. permutations of n objects taken k at a time (order counts)
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.
N!/(n-k)!
Any line connecting two points on a circle. The diameter is a chord

7. divisible by 9
N-2
N(n-1)(n-2)...(2)(1) = n!
Sum of its digits is divisible by 9
2(pir^2) + 2pirh; the two bases and the side

8. dividing fractions
Invert the second fraction and multiply them
N!/(n-k)!
Pi*r^2h
A list is ordered and can have duplicates

9. area of parallelogram
Rules for 2 and three: even and the sum of its digits is divisible by three
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
Base * height
Mean of the two middle ones

10. sides of 30/60/90 triangle
P(E and F) = P(E)P(F)
Pi*r^2h
1 - 2 - root(3); note that this is half of an equilateral triangle
1

11. x^0
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
1
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)

12. isosceles triangle
x^ab
Opposite angles formed by two intersecting lines; always congruent
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

13. area of triangle
Lwh
(n-2)(180 degrees)
1/2 base * height
(x^a)/(y^a)

14. hypotenuse
|S|
Invert the second fraction and multiply them
Side opposite the right angle
P(E and F) = P(E)P(F)

15. 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)
Last three digits (taken together) are divisible by 8
N!/k!(n-k)! which is also denotes as n choose k
(n-2)(180 degrees)

16. area of a non-right triangle
(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.
P(E or F) = P(E) + P(F)
N-2

17. differences between a set and a list
2pi*r
x^ab
Last two digits (taken together) are divisible by 4
A list is ordered and can have duplicates

18. divisible by 4
Last two digits (taken together) are divisible by 4
2pi*r
1 - 2 - root(3); note that this is half of an equilateral triangle
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.

19. how to tell if something is prime
All its interior angles are congruent
Rules for 2 and three: even and the sum of its digits is divisible by three
Any line connecting two points on a circle. The diameter is a chord
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).

20. (x^a)/(x^b)
A list is ordered and can have duplicates
Subtract the mean from each value and divide by the standard deviation
x^(a-b) or a/x^(b-a)
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.

21. volume of rectangle
1098 etc
Lwh
x^ab
Base * height

22. x^-a
A list is ordered and can have duplicates
1/x^a
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
1 if decimals - 100 if percents

23. probability of an event E
Number of outcomes yielding E / number of total outcomes
Subtract the mean from each value and divide by the standard deviation
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
2(pir^2) + 2pirh; the two bases and the side

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

25. congruency of triangles
|S|
P(E and F) = P(E)P(F)
N!/k!(n-k)! which is also denotes as n choose k
Three sides congruent - two sides and included angle - two angles and included side

26. what'S the median if there are an even number of data points?
Pi*r^2h
P(E or F) = P(E) + P(F)
Mean of the two middle ones
(xy)^a

27. sides of isoceles right triangle
1 - 1 - root(2)
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
1/2 base * height
Subtract the mean from each value and divide by the standard deviation

28. union of sets A and B
Invert the second fraction and multiply them
A + B - their intersection
Number of outcomes yielding E / number of total outcomes
N!/(n-k)!

29. vertical angles
(x^a)/(y^a)
Opposite angles formed by two intersecting lines; always congruent
1
Any line connecting two points on a circle. The diameter is a chord

30. regular polygon
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
All its interior angles are congruent
Any line connecting two points on a circle. The diameter is a chord
Invert the second fraction and multiply them

31. area of cylinder
2(pir^2) + 2pirh; the two bases and the side
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.
A list is ordered and can have duplicates

32. advantage of median
x^ab
Less affected by outliers than the mean
Side opposite the right angle
Invert the second fraction and multiply them

33. divisible by 3
A list is ordered and can have duplicates
2(pir^2) + 2pirh; the two bases and the side
Sum of its digits is divisible by 3
Invert the second fraction and multiply them

34. difference between normal or population standard deviation and the sample standard deviation
Base * height
(xy)^a
2pi*r
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

35. chord
Any line connecting two points on a circle. The diameter is a chord
x^ab
Opposite angles formed by two intersecting lines; always congruent
1 if decimals - 100 if percents

36. (x^a)(y^a)
1098 etc
(xy)^a
Side opposite the right angle
Any line connecting two points on a circle. The diameter is a chord

37. area of circle
Pi * r^2
The sum of the areas of the six faces: 2(lw + lh + wh)
|S|
P(E or F) = P(E) + P(F)

38. circumference of circle
N(n-1)(n-2)...(2)(1) = n!
Number of outcomes yielding E / number of total outcomes
2pi*r
Side opposite the right angle

39. (x^a)^b
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
(n-2)(180 degrees)
x^ab
Less affected by outliers than the mean

40. how many triangles can a polygon of n sides be divided into?
1 - 1 - root(2)
P(E and F) = P(E)P(F)
Pi*r^2h
N-2

41. volume of cylinder
Last three digits (taken together) are divisible by 8
Pi*r^2h
(n-2)(180 degrees)
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.

42. sum of measures of interior angles of a polygon with n sides
Pi*r^2h
1/x^a
1
(n-2)(180 degrees)

43. permutations of n different objects
|S|
Base * height
x^(a+b)
N(n-1)(n-2)...(2)(1) = n!

44. divisible by 6
1 - 1 - root(2)
Rules for 2 and three: even and the sum of its digits is divisible by three
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
x^ab

45. length of arc of circle
(n-2)(180 degrees)
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
x^ab

46. independence of two events E and F
P(E and F) = P(E)P(F)
Invert the second fraction and multiply them
Number of outcomes yielding E / number of total outcomes
x^(a-b) or a/x^(b-a)

47. divisible by 8
1
Last three digits (taken together) are divisible by 8
Mean of the two middle ones
Pi * r^2

48. probability that either E or F occur
Sum of its digits is divisible by 9
(xy)^a
x^(a-b) or a/x^(b-a)
P(E) + P(F) - P(E and F)

49. relationship between n choose k and n choose n-k
Pi*r^2h
1 - 1 - root(2)
Always equal - i.e. 9 choose 3 = 9 choose 6
1 - 2 - root(3); note that this is half of an equilateral triangle

50. possible combinations of three digits without allowing repeats
1098 etc
Sum of its digits is divisible by 3
2(pir^2) + 2pirh; the two bases and the side
Last three digits (taken together) are divisible by 8