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GRE Math: Common Errors

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. 5/6 in percent?
The sum of its digits is divisible by 3.
(a - b)(a + b)
The curve opens upward and the vertex is the minimal point on the graph.
83.333%

2. If you have a set of n objects - but you only want to order k of them - what formula do you use to determine the number of permutations?
N! / (n-k)!
2
The sum of its digits is divisible by 3.
Relationship cannot be determined (what if x is negative?)

3. What is the area of a regular hexagon with side 6?
3 - -3
9 : 25
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
(a - b)^2

4. If a=-1 and b=3 - what is the value of (4(a^3)(b^2) - 12(a^2)(b^5)) / (16(a^3)(b^2))?
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
F(x-c)
1 & 37/132
20.5

5. The larger the absolute value of the slope...
1
The empty set - denoted by a circle with a diagonal through it.
The steeper the slope.
x^(4+7) = x^11

6. Formula to calculate arc length?
Arc length = (n/360) x pi(2r) where n is the number of degrees.
The union of A and B.
The sum of digits is divisible by 9.
1.0843 X 10^11

7. Order of quadrants:
1
From northeast - counterclockwise. I - II - III - IV
5 OR -5
4:5

8. The objects in a set are called two names:
Members or elements
61 - 67
A tangent is a line that only touches one point on the circumference of a circle.
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)

9. Nine coins are tossed simultaneously. In how many of the outcomes will the fourth coin tossed show heads?
No - only like radicals can be added.
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
Yes - like radicals can be added/subtracted.
2^9 / 2 = 256

10. 10<all primes<20
11 - 13 - 17 - 19
From northeast - counterclockwise. I - II - III - IV
7 / 1000
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.

11. Which quadrant is the lower left hand?
37.5%
A subset.
III
Yes - like radicals can be added/subtracted.

12. Legs: 3 - 4. Hypotenuse?
Its divisible by 2 and by 3.
71 - 73 - 79
83.333%
5

13. Find the surface area of a cylinder with radius 3 and height 12.
A reflection about the axis.
90pi
No - only like radicals can be added.
The overlapping sections.

14. If the two sides of a triangle are unequal then the longer side...
27^(-4)
441000 = 1 10 10 10 21 * 21
The union of A and B.
Lies opposite the greater angle

15. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
The two xes after factoring.
A grouping of the members within a set based on a shared characteristic.
2(pi)r^2 + 2(pi)rh

16. What are the smallest three prime numbers greater than 65?
.0004809 X 10^11
67 - 71 - 73
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16

17. Factor x^2 - xy + x.
(a - b)^2
x(x - y + 1)
Undefined
3 - -3

18. Factor a^2 + 2ab + b^2
The two xes after factoring.
The set of elements which can be found in either A or B.
27^(-4)
(a + b)^2

19. If the 80th percentile of the measurements is 72degrees - about how many measurments are between 69 degrees and 72 degrees? Round your answer to the nearest tenth
18
From northeast - counterclockwise. I - II - III - IV
23 - 29
The shortest arc between points A and B on a circle'S diameter.

20. Formula for the area of a circle?
8
.0004809 X 10^11
A = pi(r^2)
The set of input values for a function.

21. A number is divisible by 9 if...
The sum of digits is divisible by 9.
An infinite set.
The interesection of A and B.
Even

22. What is the graph of f(x) shifted upward c units or spaces?
12.5%
A tangent is a line that only touches one point on the circumference of a circle.
II
F(x) + c

23. Surface area for a cylinder?
2(pi)r^2 + 2(pi)rh
(base*height) / 2
12! / 5!7! = 792
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

24. 0^0
70
Undefined
67 - 71 - 73
A reflection about the origin.

25. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
6
4:5
I
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

26. Ratio of ages of Anna and Emma is 3:5 and of Emma and Nicolas is 3:5. What is the ratio of Anna to Nicholas' ages?
Undefined - because we can'T divide by 0.
9 : 25
When the function is not defined for all real numbers -; only a subset of the real numbers.
No - only like radicals can be added.

27. What is the set of elements found in both A and B?
75:11
9 & 6/7
4.25 - 6 - 22
The interesection of A and B.

28. In a triangle where the two legs are 4 and 3 - what is the value of a line directly intersecting the middle coming from the meeting point of the two legs?
Two angles whose sum is 180.
55%
(b + c)
2.4. We calculate the area (6) and then turn the triangle on its side and use x as the height to calculate again. (5x)/2=6

29. What is the set of elements which can be found in either A or B?
(p + q)/5
62.5%
The union of A and B.
1

30. Which quadrant is the upper left hand?
31 - 37
130pi
II
37.5%

31. A number is divisible by 3 if ...
The sum of its digits is divisible by 3.
A circle centered on the origin with radius 8.
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

32. What is the 'Solution' for a system of linear equations?
No - the input value has exactly one output.
The point of intersection of the systems.
4sqrt3. The triangle can be divided into two equal 30-60-90 triangles with side 6 as the side in which 6 = xsqrt3. So x =2sqrt3...
The union of A and B.

33. A number is divisible by 6 if...
An angle which is supplementary to an interior angle.
Its divisible by 2 and by 3.
An algebraic expression is a combination of one of more terms. Terms in an expression are separated by either addition or subtraction signs. (3xy - 4ab - -5cd - x^2 + x - 1)
180 degrees

34. P and r are factors of 100. What is greater - pr or 100?
Indeterminable.
4096
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
71 - 73 - 79

35. What is an isoceles triangle?
Two equal sides and two equal angles.
70
130pi
0

36. (x^2)^4
The union of A and B.
$3 -500 in the 9% and $2 -500 in the 7%.
x^(2(4)) =x^8 = (x^4)^2
(a + b)^2

37. Evaluate 4/11 + 11/12
4sqrt3. The triangle can be divided into two equal 30-60-90 triangles with side 6 as the side in which 6 = xsqrt3. So x =2sqrt3...
A reflection about the origin.
1 & 37/132
Members or elements

38. Describe the relationship between 3x^2 and 3(x - 1)^2
x^(2(4)) =x^8 = (x^4)^2
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
72

39. (6sqrt3) x (2sqrt5) =
9 : 25
The set of elements found in both A and B.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
72

40. What is the surface area of a cylinder with radius 5 and height 8?
x^(2(4)) =x^8 = (x^4)^2
130pi
90pi
F(x) - c

41. Define an 'expression'.
A set with no members - denoted by a circle with a diagonal through it.
(b + c)
An algebraic expression is a combination of one of more terms. Terms in an expression are separated by either addition or subtraction signs. (3xy - 4ab - -5cd - x^2 + x - 1)
x^(4+7) = x^11

42. There are 10 finalists for the school spelling bee. A first - second - and third place trophy will be awarded. How many different people can get the three prizes?
N! / (k!)(n-k)!
10! / 3!(10-3)! = 120
53 - 59
II

43. What does the graph x^2 + y^2 = 64 look like?
The overlapping sections.
Triangles with same measure and same side lengths.
2^9 / 2 = 256
A circle centered on the origin with radius 8.

44. How to find the area of a sector?
75:11
67 - 71 - 73
Angle/360 x (pi)r^2
(a - b)^2

45. The slope of a line perpendicular to (a/b)?
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
F(x) - c
The sum of its digits is divisible by 3.
Its negative reciprocal. (-b/a)

46. Define a 'Term' -
A term is a numerical constant or the product (or quotient) of a numerical constant and one or more variables. (3x - 4x^2 and 2a/c)
G(x) = {x}
The curve opens upward and the vertex is the minimal point on the graph.
F(x + c)

47. Whats the difference between factors and multiples?
1
Factors are few - multiples are many.
A set with a number of elements which can be counted.
The empty set - denoted by a circle with a diagonal through it.

48. A brick with dimensions 10. 15 and 25 weighs 1.5 kg. A second brick (same density) has dimensions 12 - 18 - and 30. What is the weight of the second brick?
62.5%
1:sqrt3:2
2.592 kg
A tangent is a line that only touches one point on the circumference of a circle.

49. What is a chord of a circle?
10! / (10-3)! = 720
37.5%
A chord is a line segment joining two points on a circle.
10

50. a^2 + 2ab + b^2
1/a^6
31 - 37
3sqrt4
(a + b)^2