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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. Formula for the area of a sector of a circle?
A = pi(r^2)
1
Sector area = (n/360) X (pi)r^2
12.5%

2. What percent of 40 is 22?
55%
A tangent is a line that only touches one point on the circumference of a circle.
3
A 30-60-90 triangle.

3. (-1)^3 =
The overlapping sections.
(n-2) x 180
1
Two angles whose sum is 180.

4. Can you subtract 3sqrt4 from sqrt4?
Triangles with same measure and same side lengths.
Yes - like radicals can be added/subtracted.
90 degrees
23 - 29

5. What are 'Supplementary angles?'
A tangent is a line that only touches one point on the circumference of a circle.
y = 2x^2 - 3
Undefined
Two angles whose sum is 180.

6. Area of a triangle?
4:5
Members or elements
413.03 / 10^4 (move the decimal point 4 places to the left)
(base*height) / 2

7. 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?
2.592 kg
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
The third side is greater than the difference and less than the sum.
The objects within a set.

8. Simplify 4sqrt21 X 5sqrt2 / 10sqrt7
2sqrt6
10
A = I (1 + rt)
1/a^6

9. x^4 + x^7 =
180 degrees
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
x^(4+7) = x^11
1

10. 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?
Two angles whose sum is 180.
10! / 3!(10-3)! = 120
70
20.5

11. 5/8 in percent?
23 - 29
52
62.5%
75:11

12. How to find the area of a sector?
67 - 71 - 73
III
87.5%
Angle/360 x (pi)r^2

13. What is the ratio of the sides of an isosceles right triangle?
5 OR -5
1:1:sqrt2
The union of A and B.
2 & 3/7

14. Which quadrant is the lower left hand?
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
III
1/2 times 7/3
72

15. Factor x^2 - xy + x.
13pi / 2
x(x - y + 1)
Cd
F(x + c)

16. Order of quadrants:
Indeterminable.
From northeast - counterclockwise. I - II - III - IV
288 (8 9 4)
Move the decimal point to the right x places

17. 10<all primes<20
12sqrt2
11 - 13 - 17 - 19
Move the decimal point to the right x places
2sqrt6

18. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
180
True
87.5%
Cd

19. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
7 / 1000
180
Undefined - because we can'T divide by 0.
4:5

20. a^2 + 2ab + b^2
(a + b)^2
The empty set - denoted by a circle with a diagonal through it.
True
71 - 73 - 79

21. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
180
The greatest value minus the smallest.
28. n = 8 - k = 2. n! / k!(n-k)!
$3 -500 in the 9% and $2 -500 in the 7%.

22. Simplify the expression [(b^2 - c^2) / (b - c)]
Part = Percent X Whole
20.5
y = (x + 5)/2
(b + c)

23. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
3
IV
10! / (10-3)! = 720
II

24. The number of degrees in the largest angle of a triangle inscribed in a circle - in which the diameter of the circle is one side of the triangle.
Arc length = (n/360) x pi(2r) where n is the number of degrees.
90 degrees
Undefined - because we can'T divide by 0.
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).

25. (a^-1)/a^5
3
1/a^6
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
The point of intersection of the systems.

26. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
16.6666%
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
A central angle is an angle formed by 2 radii.
An angle which is supplementary to an interior angle.

27. What are the irrational numbers?

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28. What number between 70 & 75 - inclusive - has the greatest number of factors?
Triangles with same measure and same side lengths.
... the square of the ratios of the corresponding sides.
Indeterminable.
72

29. Evaluate 3& 2/7 / 1/3
All the numbers on the number line (negative - rational - irrational - decimal - integer). All the numbers on the GRE are real. (-2 - 1 - .25 - 1/2 - pi)
9 & 6/7
1 & 37/132
28. n = 8 - k = 2. n! / k!(n-k)!

30. If the two sides of a triangle are unequal then the longer side...
7 / 1000
Lies opposite the greater angle
The set of output values for a function.
41 - 43 - 47

31. What is the sum of the angles of a triangle?
71 - 73 - 79
1
180 degrees
441000 = 1 10 10 10 21 * 21

32. Hector invested $6000. Part was invested in account with 9% simple annual interest - and the rest in account with 7% simple annual interest. If he earned $490 in the first year of these investments - how much did he invest in each account?
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
$3 -500 in the 9% and $2 -500 in the 7%.
A = I (1 + rt)
5

33. Which quadrant is the upper right hand?
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
48
(b + c)
I

34. What is the percent formula?
Part = Percent X Whole
1:sqrt3:2
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
61 - 67

35. Define an 'expression'.
C = (pi)d
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)
12.5%
F(x + c)

36. What is a tangent?
A tangent is a line that only touches one point on the circumference of a circle.
Yes. [i.e. f(x) = x^2 - 1
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
When the function is not defined for all real numbers -; only a subset of the real numbers.

37. 3/8 in percent?
1
37.5%
An isosceles right triangle.
288 (8 9 4)

38. What is the area of a regular hexagon with side 6?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
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 set with no members - denoted by a circle with a diagonal through it.
N! / (k!)(n-k)!

39. 50 < all primes< 60
The curve opens downward and the vertex is the maximum point on the graph.
53 - 59
1.7
28. n = 8 - k = 2. n! / k!(n-k)!

40. Write 10 -843 X 10^7 in scientific notation
1.0843 X 10^11
2 & 3/7
1 & 37/132
The set of elements found in both A and B.

41. a^2 - b^2
The direction of the inequality is reversed.
62.5%
9 & 6/7
(a - b)(a + b)

42. Legs 6 - 8. Hypotenuse?
An angle which is supplementary to an interior angle.
1
F(x) - c
10

43. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
500
A circle centered at -2 - -2 with radius 3.
4a^2(b)
I

44. Formula to find a circle'S circumference from its diameter?
2(pi)r^2 + 2(pi)rh
The curve opens upward and the vertex is the minimal point on the graph.
C = (pi)d
0

45. How many sides does a hexagon have?
11 - 13 - 17 - 19
A reflection about the origin.
6
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15

46. What is the formula for computing simple interest?
4.25 - 6 - 22
An expression with just one term (-6x - 2a^2)
A = I (1 + rt)
The set of elements found in both A and B.

47. Volume for a cylinder?
Area of the base X height = (pi)hr^2
The point of intersection of the systems.
Its divisible by 2 and by 3.
Undefined - because we can'T divide by 0.

48. What does the graph x^2 + y^2 = 64 look like?
67 - 71 - 73
A circle centered on the origin with radius 8.
A tangent is a line that only touches one point on the circumference of a circle.
(a - b)^2

49. Suppose you have a set of n objects - and you want to select k of them - but the order doesn'T matter. What formula do you use to determine the number of combinations of n objects taken k at a time?
71 - 73 - 79
2
The union of A and B.
N! / (k!)(n-k)!

50. x^2 = 9. What is the value of x?
The overlapping sections.
72
9 & 6/7
3 - -3