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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. advantage of median
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
N(n-1)(n-2)...(2)(1) = n!
x^ab
Less affected by outliers than the mean

2. union of sets A and B
A + B - their intersection
101010
Pi * r^2
1/2 base * height

3. standardization/normalization
A + B - their intersection
101010
Subtract the mean from each value and divide by the standard deviation
At least two congruent sides; the angles opposite these sides are also congruent

4. (x^a)(x^b)
x^(a+b)
1 - 2 - root(3); note that this is half of an equilateral triangle
x^ab
N-2

5. hypotenuse
Rules for 2 and three: even and the sum of its digits is divisible by three
Side opposite the right angle
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
All its interior angles are congruent

6. sides of isoceles right triangle
1 - 1 - root(2)
Invert the second fraction and multiply them
A + B - their intersection
N(n-1)(n-2)...(2)(1) = n!

7. x^-a
1/x^a
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
The sum of the areas of the six faces: 2(lw + lh + wh)

8. (x^a)/(x^b)
(n-2)(180 degrees)
All its interior angles are congruent
Number of outcomes yielding E / number of total outcomes
x^(a-b) or a/x^(b-a)

9. (x/y)^a
P(E and F) = P(E)P(F)
A + B - their intersection
(x^a)/(y^a)
x^(a+b)

10. how to tell if something is prime
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
(n-2)(180 degrees)
Divide it by the prime numbers from 2 to the closest to the square root of the number (round down).
N!/(n-k)!

11. area of parallelogram
1/2 base * height
x^(a-b) or a/x^(b-a)
Base * height
P(E) + P(F) - P(E and F)

12. difference between normal or population standard deviation and the sample standard deviation
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
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/x^a
P(E) + P(F) - P(E and F)

13. area of rectangle
Any line connecting two points on a circle. The diameter is a chord
1/2 base * height
The sum of the areas of the six faces: 2(lw + lh + wh)
P(E) + P(F) - P(E and F)

14. permutations of n objects taken k at a time (order counts)
N!/(n-k)!
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
Pi*r^2h

15. area of sector of circle
A + B - their intersection
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).
2(pir^2) + 2pirh; the two bases and the side

16. divisible by 3
Sum of its digits is divisible by 3
|S|
101010
All its interior angles are congruent

17. area of triangle
1/2 base * height
x^ab
Pi*r^2h
Three sides congruent - two sides and included angle - two angles and included side

18. sides of 30/60/90 triangle
(n-2)(180 degrees)
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
A list is ordered and can have duplicates

19. x^0
Pi*r^2h
1
Number of outcomes yielding E / number of total outcomes
Opposite angles formed by two intersecting lines; always congruent

20. divisible by 4
Rules for 2 and three: even and the sum of its digits is divisible by three
Number of outcomes yielding E / number of total outcomes
Last two digits (taken together) are divisible by 4
Lwh

21. (x^a)^b
Last three digits (taken together) are divisible by 8
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
x^ab
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.

22. probability that either E or F occur
P(E) + P(F) - P(E and F)
|S|
1 - 2 - root(3); note that this is half of an equilateral triangle
1 - 1 - root(2)

23. differences between a set and a list
A list is ordered and can have duplicates
Base * height
All its interior angles are congruent
x^(a-b) or a/x^(b-a)

24. (x^a)(y^a)
(x^a)/(y^a)
(xy)^a
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
1 if decimals - 100 if percents

25. similar triangles
2pi*r
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
P(E or F) = P(E) + P(F)
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

26. sum of measures of interior angles of a polygon with n sides
P(E and F) = P(E)P(F)
Sum of its digits is divisible by 3
(x^a)/(y^a)
(n-2)(180 degrees)

27. sum of relative frequencies in a frequency distribution
Sum of its digits is divisible by 3
1 if decimals - 100 if percents
x^(a+b)
N(n-1)(n-2)...(2)(1) = n!

28. mutually exclusive
N!/(n-k)!
P(E or F) = P(E) + P(F)
x^(a-b) or a/x^(b-a)
Any line connecting two points on a circle. The diameter is a chord

29. possible combinations of three digits allowing repeats
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
Less affected by outliers than the mean
1 if decimals - 100 if percents
101010

30. dividing fractions
Invert the second fraction and multiply them
Subtract the mean from each value and divide by the standard deviation
P(E or F) = P(E) + P(F)
N!/k!(n-k)! which is also denotes as n choose k

31. chord
x^ab
Any line connecting two points on a circle. The diameter is a chord
Invert the second fraction and multiply them
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.

32. permutations of n different objects
At least two congruent sides; the angles opposite these sides are also congruent
N(n-1)(n-2)...(2)(1) = n!
N!/(n-k)!
Opposite angles formed by two intersecting lines; always congruent

33. probability of an event E
Invert the second fraction and multiply them
Number of outcomes yielding E / number of total outcomes
N!/(n-k)!
Rules for 2 and three: even and the sum of its digits is divisible by three

34. divisible by 9
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
Sum of its digits is divisible by 9
Any line connecting two points on a circle. The diameter is a chord
Invert the second fraction and multiply them

35. what'S the median if there are an even number of data points?
Mean of the two middle ones
x^(a+b)
All its interior angles are congruent
N-2

36. area of trapezoid
Sum of its digits is divisible by 9
1/2(b1 + b2)h - where b1 and b2 are the two parallel sides
All its interior angles are congruent
N!/(n-k)!

37. regular polygon
2(pir^2) + 2pirh; the two bases and the side
Pi*r^2h
x^(a+b)
All its interior angles are congruent

38. volume of cylinder
P(E) + P(F) - P(E and F)
At least two congruent sides; the angles opposite these sides are also congruent
1 - 1 - root(2)
Pi*r^2h

39. divisible by 8
Last three digits (taken together) are divisible by 8
Congruent angles (check this to be sure) but possibly different size. Can use proportions to get other values by cross-multiplication
N!/k!(n-k)! which is also denotes as n choose k
Subtract the mean from each value and divide by the standard deviation

40. congruency of triangles
N!/(n-k)!
P(E and F) = P(E)P(F)
Three sides congruent - two sides and included angle - two angles and included side
A list is ordered and can have duplicates

41. 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
Pi*r^2h

42. divisible by 11
(1st digit + 3rd + 5th...) - (2nd + 4th + 6th...) is divisible by 11.
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
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
At least two congruent sides; the angles opposite these sides are also congruent

43. independence of two events E and F
A + B - their intersection
P(E and F) = P(E)P(F)
P(E or F) = P(E) + P(F)
Subtract the mean from each value and divide by the standard deviation

44. relationship between n choose k and n choose n-k
Always equal - i.e. 9 choose 3 = 9 choose 6
Less affected by outliers than the mean
2(pir^2) + 2pirh; the two bases and the side
Subtract the mean from each value and divide by the standard deviation

45. volume of rectangle
(xy)^a
Sum of its digits is divisible by 9
Lwh
Pi * r^2

46. vertical angles
Opposite angles formed by two intersecting lines; always congruent
2pi*r
A list is ordered and can have duplicates
(xy)^a

47. isosceles triangle
At least two congruent sides; the angles opposite these sides are also congruent
N!/k!(n-k)! which is also denotes as n choose k
2(pir^2) + 2pirh; the two bases and the side
Sum of its digits is divisible by 9

48. area of a non-right triangle
x^(a-b) or a/x^(b-a)
Still bh/2 - but you can draw h as a line perpendicular to an extension of any side you take as the base.
N!/(n-k)!
Base * height

49. possible combinations of three digits without allowing repeats
Pi * r^2
1098 etc
Opposite angles formed by two intersecting lines; always congruent
Number of outcomes yielding E / number of total outcomes

50. length of arc of circle
Length of arc has the same proportion to the circumference that the arc measure (angle) has to 360 degrees.
Sum of its digits is divisible by 9
x^ab
1 if decimals - 100 if percents