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GRE Math: Common Errors

Subjects : gre, math

Instructions:

Answer 50 questions in 15 minutes.
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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. What is the formula for compounded interest?
1/2 times 7/3
I
4725
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.

2. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
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)
No - only like radicals can be added.
A circle centered at -2 - -2 with radius 3.
13

3. What is the surface area of a cylinder with radius 5 and height 8?
A = I (1 + rt)
An isosceles right triangle.
130pi
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15

4. 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.
The shortest arc between points A and B on a circle'S diameter.
0
500

5. 1/2 divided by 3/7 is the same as
The set of output values for a function.
Two equal sides and two equal angles.
1/2 times 7/3
23 - 29

6. How many sides does a hexagon have?
Two equal sides and two equal angles.
3
The set of output values for a function.
6

7. Legs 6 - 8. Hypotenuse?
No - the input value has exactly one output.
No - only like radicals can be added.
An expression with just one term (-6x - 2a^2)
10

8. How to determine percent increase?
The sum of its digits is divisible by 3.
The set of elements found in both A and B.
(amount of increase/original price) x 100%
288 (8 9 4)

9. Which is greater? 200x^295 or 10x^294?
The objects within a set.
Relationship cannot be determined (what if x is negative?)
x^(6-3) = x^3
71 - 73 - 79

10. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
13pi / 2
$3 -500 in the 9% and $2 -500 in the 7%.
Two angles whose sum is 180.
The sum of its digits is divisible by 3.

11. Define a 'Term' -
10
A circle centered on the origin with radius 8.
The overlapping sections.
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)

12. What is a chord of a circle?
10
A chord is a line segment joining two points on a circle.
A reflection about the origin.
37.5%

13. Nine coins are tossed simultaneously. In how many of the outcomes will the fourth coin tossed show heads?
2^9 / 2 = 256
...multiply by 100.
1/a^6
1

14. Number of degrees in a triangle
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
180
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)

15. 5 bakeries sell an average of 300 muffins per bakery per day. If 2 stop making muffins but the total muffins sold stays the same - what is the average of muffins per bakery sold among the remaining?
1:1:sqrt2
I
500
The set of output values for a function.

16. What is the slope of a vertical line?
2.592 kg
8
Undefined - because we can'T divide by 0.
2(pi)r^2 + 2(pi)rh

17. How to determine percent decrease?
1/(x^y)
(amount of decrease/original price) x 100%
A reflection about the origin.
2(pi)r^2 + 2(pi)rh

18. What are the irrational numbers?
37.5%
12! / 5!7! = 792
90
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)

19. Which is greater? 27^(-4) or 9^(-8)
27^(-4)
Even
75:11
An isosceles right triangle.

20. Factor a^2 + 2ab + b^2
70
5 OR -5
7 / 1000
(a + b)^2

21. For similar triangles - the ratio of their corresponding sides is 2:3. What is the ratio of their areas?
16.6666%
Yes. [i.e. f(x) = x^2 - 1
55%
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.

22. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
62.5%
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
An isosceles right triangle.

23. Factor x^2 - xy + x.
37.5%
(a + b)^2
No - only like radicals can be added.
x(x - y + 1)

24. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
4725
Undefined - because we can'T divide by 0.
3 - -3
13

25. 40 < all primes<50
41 - 43 - 47
When the function is not defined for all real numbers -; only a subset of the real numbers.
The objects within a set.
C = (pi)d

26. 5/8 in percent?
I
Part = Percent X Whole
62.5%
4.25 - 6 - 22

27. What is a minor arc?
87.5%
Sector area = (n/360) X (pi)r^2
The shortest arc between points A and B on a circle'S diameter.
G(x) = {x}

28. What does the graph x^2 + y^2 = 64 look like?
A circle centered on the origin with radius 8.
The greatest value minus the smallest.
A circle centered at -2 - -2 with radius 3.
2

29. 1/8 in percent?
12.5%
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
(a - b)(a + b)
83.333%

30. (6sqrt3) x (2sqrt5) =
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
Undefined - because we can'T divide by 0.
The set of input values for a function.

31. What is the graph of f(x) shifted upward c units or spaces?
Indeterminable.
The curve opens upward and the vertex is the minimal point on the graph.
F(x) + c
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)

32. 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?
72
N! / (k!)(n-k)!
y = (x + 5)/2
IV

33. 10<all primes<20
11 - 13 - 17 - 19
3
6
1

34. 1/6 in percent?
2(pi)r^2 + 2(pi)rh
16.6666%
70
3/2 - 5/3

35. Formula for the area of a circle?
31 - 37
A = pi(r^2)
True
62.5%

36. 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))?
20.5
The longest arc between points A and B on a circle'S diameter.
4096
(b + c)

37. If r - t - s & u are distinct - consecutive prime numbers - less than 31 - which of the following could be an average of them (4 - 4.25 - 6 - 9 - 24 - 22 - 24)
4.25 - 6 - 22
I
IV
12sqrt2

38. 5x^2 - 35x -55 = 0
The two xes after factoring.
3
y = 2x^2 - 3
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]

39. a^2 - 2ab + b^2
(a - b)^2
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
Arc length = (n/360) x pi(2r) where n is the number of degrees.
1/2 times 7/3

40. What is the measure of an exterior angle of a regular pentagon?
13
(p + q)/5
From northeast - counterclockwise. I - II - III - IV
72

41. What is a central angle?
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
An infinite set.
72
A central angle is an angle formed by 2 radii.

42. What does scientific notation mean?
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
1
y = (x + 5)/2
90

43. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
48
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
A reflection about the axis.
The set of elements which can be found in either A or B.

44. 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?
48
From northeast - counterclockwise. I - II - III - IV
(a - b)^2
10! / (10-3)! = 720

45. What is the graph of f(x) shifted downward c units or spaces?
F(x) - c
500
41 - 43 - 47
$3 -500 in the 9% and $2 -500 in the 7%.

46. What is the area of a regular hexagon with side 6?
72
A reflection about the axis.
...multiply by 100.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

47. When the 'a' in the parabola is negative...
A reflection about the axis.
The curve opens downward and the vertex is the maximum point on the graph.
67 - 71 - 73
C = (pi)d

48. Write 10 -843 X 10^7 in scientific notation
1.0843 X 10^11
Infinite.
1/(x^y)
2

49. 10^6 has how many zeroes?
F(x) + c
2^9 / 2 = 256
10
6

50. The perimeter of a square is 48 inches. The length of its diagonal is:
12sqrt2
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
2 & 3/7
G(x) = {x}

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