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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. sum of relative frequencies in a frequency distribution
N-2
Opposite angles formed by two intersecting lines; always congruent
Rules for 2 and three: even and the sum of its digits is divisible by three
1 if decimals - 100 if percents

2. hypotenuse
A list is ordered and can have duplicates
Base * height
Side opposite the right angle
Three sides congruent - two sides and included angle - two angles and included side

3. (x/y)^a
N-2
Last three digits (taken together) are divisible by 8
(x^a)/(y^a)
Side opposite the right angle

4. combinations of n objects taken k at a time (order doesn'T count)
Mean of the two middle ones
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
1098 etc

5. possible combinations of three digits without allowing repeats
Number of outcomes yielding E / number of total outcomes
Lwh
1098 etc
N(n-1)(n-2)...(2)(1) = n!

6. mutually exclusive
Three sides congruent - two sides and included angle - two angles and included side
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
P(E or F) = P(E) + P(F)
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides

7. relationship between n choose k and n choose n-k
(xy)^a
Always equal - i.e. 9 choose 3 = 9 choose 6
Last three digits (taken together) are divisible by 8
All its interior angles are congruent

8. area of triangle
1/2 base * height
1 if decimals - 100 if percents
Three sides congruent - two sides and included angle - two angles and included side
Less affected by outliers than the mean

9. volume of rectangle
All its interior angles are congruent
(xy)^a
Invert the second fraction and multiply them
Lwh

10. differences between a set and a list
A list is ordered and can have duplicates
Any line connecting two points on a circle. The diameter is a chord
x^ab
Side opposite the right angle

11. number of elements in set S
Always equal - i.e. 9 choose 3 = 9 choose 6
2(pir^2) + 2pirh; the two bases and the side
The sum of the areas of the six faces: 2(lw + lh + wh)
|S|

12. area of trapezoid
The sum of the areas of the six faces: 2(lw + lh + wh)
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
N-2

13. chord
P(E and F) = P(E)P(F)
(x^a)/(y^a)
Any line connecting two points on a circle. The diameter is a chord
N(n-1)(n-2)...(2)(1) = n!

14. independence of two events E and F
P(E and F) = P(E)P(F)
1/2 base * height
Sum of its digits is divisible by 9
Less affected by outliers than the mean

15. permutations of n different objects
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
N(n-1)(n-2)...(2)(1) = n!
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

16. advantage of median
(xy)^a
1
2pi*r
Less affected by outliers than the mean

17. area of cylinder
2(pir^2) + 2pirh; the two bases and the side
x^ab
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
The sum of the areas of the six faces: 2(lw + lh + wh)

18. dividing fractions
1 - 2 - root(3); note that this is half of an equilateral triangle
Pi * r^2
(xy)^a
Invert the second fraction and multiply them

19. area of rectangle
(n-2)(180 degrees)
Less affected by outliers than the mean
The sum of the areas of the six faces: 2(lw + lh + wh)
Invert the second fraction and multiply them

20. how to tell if something is prime
At least two congruent sides; the angles opposite these sides are also congruent
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
All its interior angles are congruent
Side opposite the right angle

21. x^-a
Three sides congruent - two sides and included angle - two angles and included side
N!/k!(n-k)! which is also denotes as n choose k
1/x^a
Pi * r^2

22. union of sets A and B
N-2
Mean of the two middle ones
1
A + B - their intersection

23. area of a non-right triangle
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
At least two congruent sides; the angles opposite these sides are also congruent
x^ab
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.

24. divisible by 9
N(n-1)(n-2)...(2)(1) = n!
Less affected by outliers than the mean
P(E and F) = P(E)P(F)
Sum of its digits is divisible by 9

25. volume of cylinder
Pi*r^2h
Last two digits (taken together) are divisible by 4
The sum of the areas of the six faces: 2(lw + lh + wh)
Area of sector has the same proportion to the total area that the arc measure (angle) has to 360 degrees.

26. divisible by 6
Rules for 2 and three: even and the sum of its digits is divisible by three
Lwh
|S|
1

27. area of circle
Opposite angles formed by two intersecting lines; always congruent
Pi*r^2h
A list is ordered and can have duplicates
Pi * r^2

28. (x^a)(y^a)
x^(a+b)
Lwh
Opposite angles formed by two intersecting lines; always congruent
(xy)^a

29. divisible by 3
Sum of its digits is divisible by 3
1 - 1 - root(2)
A list is ordered and can have duplicates
At least two congruent sides; the angles opposite these sides are also congruent

30. similar triangles
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
Any line connecting two points on a circle. The diameter is a chord
Sum of its digits is divisible by 9
2pi*r

31. 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
Pi * r^2
2pi*r
Last three digits (taken together) are divisible by 8

32. length of arc of circle
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
N-2
x^(a+b)
P(E and F) = P(E)P(F)

33. regular polygon
Side opposite the right angle
Three sides congruent - two sides and included angle - two angles and included side
All its interior angles are congruent
x^(a-b) or a/x^(b-a)

34. area of parallelogram
At least two congruent sides; the angles opposite these sides are also congruent
Less affected by outliers than the mean
Base * height
1/2 base * height

35. probability that either E or F occur
Mean of the two middle ones
P(E) + P(F) - P(E and F)
2(pir^2) + 2pirh; the two bases and the side
x^(a-b) or a/x^(b-a)

36. probability of an event E
Number of outcomes yielding E / number of total outcomes
(x^a)/(y^a)
Lwh
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.

37. divisible by 11
x^(a-b) or a/x^(b-a)
Any line connecting two points on a circle. The diameter is a chord
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
Pi * r^2

38. possible combinations of three digits allowing repeats
1 - 1 - root(2)
101010
N!/k!(n-k)! which is also denotes as n choose k
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication

39. x^0
Side opposite the right angle
1/2 base * height
1
Base * height

40. divisible by 8
At least two congruent sides; the angles opposite these sides are also congruent
The sum of the areas of the six faces: 2(lw + lh + wh)
Less affected by outliers than the mean
Last three digits (taken together) are divisible by 8

41. isosceles triangle
At least two congruent sides; the angles opposite these sides are also congruent
Last three digits (taken together) are divisible by 8
N(n-1)(n-2)...(2)(1) = n!
2(pir^2) + 2pirh; the two bases and the side

42. permutations of n objects taken k at a time (order counts)
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
N!/(n-k)!
Last two digits (taken together) are divisible by 4

43. sum of measures of interior angles of a polygon with n sides
(n-2)(180 degrees)
All its interior angles are congruent
N!/k!(n-k)! which is also denotes as n choose k
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.

44. standardization/normalization
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
(x^a)/(y^a)
Subtract the mean from each value and divide by the standard deviation

45. divisible by 4
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
Last two digits (taken together) are divisible by 4
N-2
Sum of its digits is divisible by 3

46. (x^a)(x^b)
Three sides congruent - two sides and included angle - two angles and included side
Mean of the two middle ones
x^(a+b)
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.

47. sides of 30/60/90 triangle
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
2pi*r
Side opposite the right angle
1 - 2 - root(3); note that this is half of an equilateral triangle

48. circumference of circle
Always equal - i.e. 9 choose 3 = 9 choose 6
x^(a-b) or a/x^(b-a)
2pi*r
All its interior angles are congruent

49. what'S the median if there are an even number of data points?
Rules for 2 and three: even and the sum of its digits is divisible by three
2pi*r
1
Mean of the two middle ones

50. how many triangles can a polygon of n sides be divided into?
1 - 1 - root(2)
N-2
Invert the second fraction and multiply them
(x^a)/(y^a)