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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. area of rectangle
(n-2)(180 degrees)
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
Side opposite the right angle
The sum of the areas of the six faces: 2(lw + lh + wh)

2. isosceles triangle
Subtract the mean from each value and divide by the standard deviation
1/x^a
All its interior angles are congruent
At least two congruent sides; the angles opposite these sides are also congruent

3. number of elements in set S
Opposite angles formed by two intersecting lines; always congruent
1098 etc
|S|
Pi*r^2h

4. permutations of n different objects
Opposite angles formed by two intersecting lines; always congruent
N(n-1)(n-2)...(2)(1) = n!
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
2pi*r

5. how many triangles can a polygon of n sides be divided into?
2pi*r
N-2
Sum of its digits is divisible by 9
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).

6. x^0
1
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
x^(a+b)
Always equal - i.e. 9 choose 3 = 9 choose 6

7. divisible by 6
1/x^a
Side opposite the right angle
Rules for 2 and three: even and the sum of its digits is divisible by three
(xy)^a

8. divisible by 9
x^(a-b) or a/x^(b-a)
Base * height
Sum of its digits is divisible by 9
Less affected by outliers than the mean

9. divisible by 3
A + B - their intersection
Sum of its digits is divisible by 3
101010
|S|

10. (x^a)(y^a)
1 if decimals - 100 if percents
Pi * r^2
(xy)^a
x^ab

11. similar triangles
x^(a-b) or a/x^(b-a)
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
A + B - their intersection
N!/k!(n-k)! which is also denotes as n choose k

12. area of cylinder
1
2(pir^2) + 2pirh; the two bases and the side
P(E) + P(F) - P(E and F)
Sum of its digits is divisible by 9

13. divisible by 11
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
Sum of its digits is divisible by 9
N!/k!(n-k)! which is also denotes as n choose k

14. area of parallelogram
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
Base * height
2pi*r

15. sides of 30/60/90 triangle
All its interior angles are congruent
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
1 - 2 - root(3); note that this is half of an equilateral triangle
A list is ordered and can have duplicates

16. regular polygon
x^(a-b) or a/x^(b-a)
Less affected by outliers than the mean
1/2 base * height
All its interior angles are congruent

17. combinations of n objects taken k at a time (order doesn'T count)
1098 etc
N!/k!(n-k)! which is also denotes as n choose k
Subtract the mean from each value and divide by the standard deviation
Three sides congruent - two sides and included angle - two angles and included side

18. area of circle
|S|
1098 etc
Pi * r^2
Invert the second fraction and multiply them

19. standardization/normalization
Subtract the mean from each value and divide by the standard deviation
Sum of its digits is divisible by 9
N-2
1098 etc

20. permutations of n objects taken k at a time (order counts)
N!/(n-k)!
Side opposite the right angle
Pi * r^2
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).

21. advantage of median
Less affected by outliers than the mean
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
N!/k!(n-k)! which is also denotes as n choose k
x^ab

22. (x^a)(x^b)
1098 etc
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
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.
x^(a+b)

23. area of sector of circle
1/x^a
1 - 2 - root(3); note that this is half of an equilateral triangle
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.

24. (x^a)^b
Side opposite the right angle
Sum of its digits is divisible by 9
1 - 1 - root(2)
x^ab

25. mutually exclusive
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.
P(E or F) = P(E) + P(F)
Less affected by outliers than the mean

26. relationship between n choose k and n choose n-k
2pi*r
1098 etc
Always equal - i.e. 9 choose 3 = 9 choose 6
P(E) + P(F) - P(E and F)

27. (x/y)^a
(n-2)(180 degrees)
A list is ordered and can have duplicates
The sum of the areas of the six faces: 2(lw + lh + wh)
(x^a)/(y^a)

28. volume of rectangle
Lwh
Mean of the two middle ones
(x^a)/(y^a)
P(E and F) = P(E)P(F)

29. possible combinations of three digits without allowing repeats
1098 etc
P(E and F) = P(E)P(F)
Pi * r^2
Three sides congruent - two sides and included angle - two angles and included side

30. how to tell if something is prime
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.
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

31. area of trapezoid
Lwh
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
Invert the second fraction and multiply them
1098 etc

32. probability that either E or F occur
Pi * r^2
A + B - their intersection
P(E) + P(F) - P(E and F)
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides

33. chord
Less affected by outliers than the mean
N-2
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

34. sum of measures of interior angles of a polygon with n sides
P(E or F) = P(E) + P(F)
Three sides congruent - two sides and included angle - two angles and included side
2pi*r
(n-2)(180 degrees)

35. dividing fractions
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
Invert the second fraction and multiply them
Less affected by outliers than the mean

36. differences between a set and a list
A list is ordered and can have duplicates
Pi*r^2h
The sum of the areas of the six faces: 2(lw + lh + wh)
P(E and F) = P(E)P(F)

37. union of sets A and B
A + B - their intersection
Less affected by outliers than the mean
The sum of the areas of the six faces: 2(lw + lh + wh)
Pi*r^2h

38. divisible by 8
Subtract the mean from each value and divide by the standard deviation
Number of outcomes yielding E / number of total outcomes
Last three digits (taken together) are divisible by 8
2pi*r

39. difference between normal or population standard deviation and the sample standard deviation
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
Always equal - i.e. 9 choose 3 = 9 choose 6
Sum of its digits is divisible by 9
N-2

40. hypotenuse
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
P(E) + P(F) - P(E and F)
Side opposite the right angle
P(E or F) = P(E) + P(F)

41. volume of cylinder
1 if decimals - 100 if percents
Subtract the mean from each value and divide by the standard deviation
Pi*r^2h
1 - 1 - root(2)

42. what'S the median if there are an even number of data points?
Lwh
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!
Mean of the two middle ones

43. vertical angles
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 - root(2)
N-2
Opposite angles formed by two intersecting lines; always congruent

44. area of triangle
P(E and F) = P(E)P(F)
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.
1/2 base * height

45. divisible by 4
Sum of its digits is divisible by 3
Last two digits (taken together) are divisible by 4
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
Subtract the mean from each value and divide by the standard deviation

46. length of arc of circle
Sum of its digits is divisible by 3
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
Pi * r^2
(x^a)/(y^a)

47. sides of isoceles right triangle
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
1 - 1 - root(2)
Base * height
Side opposite the right angle

48. (x^a)/(x^b)
N(n-1)(n-2)...(2)(1) = n!
x^(a-b) or a/x^(b-a)
Opposite angles formed by two intersecting lines; always congruent
Subtract the mean from each value and divide by the standard deviation

49. area of a non-right triangle
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
Last two digits (taken together) are divisible by 4
A list is ordered and can have duplicates
1 - 1 - root(2)

50. circumference of circle
Subtract the mean from each value and divide by the standard deviation
101010
2pi*r
Last three digits (taken together) are divisible by 8