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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. 25^(1/2) or sqrt. 25 =
5 OR -5
(a - b)(a + b)
31 - 37
Area of the base X height = (pi)hr^2

2. What number between 70 & 75 - inclusive - has the greatest number of factors?
16.6666%
The direction of the inequality is reversed.
72
Undefined

3. Circumference of a circle?
Diameter(Pi)
3/2 - 5/3
Two angles whose sum is 90.
2 & 3/7

4. Factor a^2 + 2ab + b^2
Move the decimal point to the right x places
(a + b)^2
Two angles whose sum is 90.
500

5. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
A 30-60-90 triangle.
An angle which is supplementary to an interior angle.
A subset.
Infinite.

6. 30< all primes<40
Its divisible by 2 and by 3.
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
180
31 - 37

7. How to find the circumference of a circle which circumscribes a square?
6 : 1 : 2
2(pi)r^2 + 2(pi)rh
A = pi(r^2)
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).

8. What is a piecewise equation?
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
y = 2x^2 - 3
A grouping of the members within a set based on a shared characteristic.
2 & 3/7

9. 1/8 in percent?
An infinite set.
3
12.5%
Ax^2 + bx + c where a -b and c are constants and a /=0

10. 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
Angle/360 x 2(pi)r
(a - b)(a + b)
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

11. If an inequality is multiplied or divided by a negative number....
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
Its divisible by 2 and by 3.
The direction of the inequality is reversed.
75:11

12. What is the third quartile of the following data set: 44 - 58 - 63 - 63 - 68 - 70 - 82
67 - 71 - 73
3
F(x) - c
70

13. Formula to find a circle'S circumference from its diameter?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
C = (pi)d
x^(6-3) = x^3

14. What is a subset?
A grouping of the members within a set based on a shared characteristic.
87.5%
41 - 43 - 47
The shortest arc between points A and B on a circle'S diameter.

15. What is the absolute value function?
12sqrt2
A set with no members - denoted by a circle with a diagonal through it.
G(x) = {x}
A reflection about the axis.

16. 20<all primes<30
23 - 29
130pi
True
$11 -448

17. Legs: 3 - 4. Hypotenuse?
12! / 5!7! = 792
72
5
6

18. x^4 + x^7 =
A= I (1 + (r/c))^tC - where I is the investment - C is the number of times compounded annually - and t is the number of years.
x^(4+7) = x^11
Its negative reciprocal. (-b/a)
3

19. Can the input value of a function have more than one output value (i.e. x: y - y1)?
No - the input value has exactly one output.
(base*height) / 2
20.5
3

20. The objects in a set are called two names:
12! / 5!7! = 792
Members or elements
Arc length = (n/360) x pi(2r) where n is the number of degrees.
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

21. What is the measure of an exterior angle of a regular pentagon?
A circle centered on the origin with radius 8.
72
4.25 - 6 - 22
Cd

22. A number is divisible by 4 is...
Its last two digits are divisible by 4.
61 - 67
A set with no members - denoted by a circle with a diagonal through it.
12! / 5!7! = 792

23. Reduce: 4.8 : 0.8 : 1.6
53 - 59
(p + q)/5
An expression with just one term (-6x - 2a^2)
6 : 1 : 2

24. (a^-1)/a^5
The overlapping sections.
3
x^(6-3) = x^3
1/a^6

25. Evaluate and write as a mixed number: 2/7 - 3/21 + 2 & 4/14
48
2 & 3/7
Triangles with same measure and same side lengths.
10! / (10-3)! = 720

26. A number is divisible by 3 if ...
A grouping of the members within a set based on a shared characteristic.
41 - 43 - 47
The sum of its digits is divisible by 3.
Two equal sides and two equal angles.

27. Evaluate 4/11 + 11/12
1 & 37/132
G(x) = {x}
The curve opens upward and the vertex is the minimal point on the graph.
Its negative reciprocal. (-b/a)

28. Define a 'monomial'
No - only like radicals can be added.
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
An expression with just one term (-6x - 2a^2)
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

29. What is a chord of a circle?
F(x + c)
A chord is a line segment joining two points on a circle.
When the function is not defined for all real numbers -; only a subset of the real numbers.
Its negative reciprocal. (-b/a)

30. What is the surface area of a cylinder with radius 5 and height 8?
20.5
130pi
1
5 OR -5

31. Can you simplify sqrt72?
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
180
1/2 times 7/3
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.

32. 10<all primes<20
II
62.5%
11 - 13 - 17 - 19
x^(4+7) = x^11

33. Formula for the area of a circle?
87.5%
Triangles with same measure and same side lengths.
II
A = pi(r^2)

34. What is the name of set with a number of elements which cannot be counted?
Sector area = (n/360) X (pi)r^2
9 : 25
An infinite set.
1:1:sqrt2

35. What is an isoceles triangle?
y = (x + 5)/2
Two equal sides and two equal angles.
(a + b)^2
The empty set - denoted by a circle with a diagonal through it.

36. 1/2 divided by 3/7 is the same as
The greatest value minus the smallest.
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
The set of elements found in both A and B.
1/2 times 7/3

37. Order of quadrants:
From northeast - counterclockwise. I - II - III - IV
The longest arc between points A and B on a circle'S diameter.
13pi / 2
12sqrt2

38. A number is divisible by 6 if...
Its divisible by 2 and by 3.
Its last two digits are divisible by 4.
(a + b)^2
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16

39. Employee X is paid 19.50 per hour no matter how many a week. Employee Y earns 18 for the first 40 and 1.5 the hourly wage for every hour after that. If both earned the same amount and worked the same in one week - how many did each work?
Its last two digits are divisible by 4.
48
(a - b)^2
12.5%

40. a^2 - b^2
71 - 73 - 79
5
2^9 / 2 = 256
(a - b)(a + b)

41. Formula to calculate arc length?
2
x^(6-3) = x^3
27^(-4)
Arc length = (n/360) x pi(2r) where n is the number of degrees.

42. What is a set with no members called?
1.7
An angle which is supplementary to an interior angle.
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
The empty set - denoted by a circle with a diagonal through it.

43. What is the graph of f(x) shifted right c units or spaces?
1.7
180
The set of input values for a function.
F(x-c)

44. (6sqrt3) x (2sqrt5) =
The third side is greater than the difference and less than the sum.
2 & 3/7
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
37.5%

45. Formula of rectangle where l increases by 20% and w decreases by 20%
No - the input value has exactly one output.
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
4a^2(b)
x= (1.2)(.8)lw

46. Formula for the area of a sector of a circle?
Ax^2 + bx + c where a -b and c are constants and a /=0
75:11
The sum of digits is divisible by 9.
Sector area = (n/360) X (pi)r^2

47. What are the rational numbers?
2
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
The sum of its digits is divisible by 3.
10! / (10-3)! = 720

48. 1/6 in percent?
16.6666%
x(x - y + 1)
4a^2(b)
(b + c)

49. 50 < all primes< 60
2
N! / (k!)(n-k)!
53 - 59
41 - 43 - 47

50. Is 0 even or odd?
(a - b)(a + b)
Even
The set of input values for a function.
I