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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. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
The point of intersection of the systems.
12! / 5!7! = 792
180 degrees
441000 = 1 10 10 10 21 * 21

2. What is the area of a regular hexagon with side 6?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
3 - -3
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
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...

3. 40 < all primes<50
4a^2(b)
F(x-c)
12sqrt2
41 - 43 - 47

4. If Madagascar'S exports totaled 1.3 billion in 2009 - and 4% came from China - what was the value in millions of the country'S exports to China?
87.5%
I
Pi is the ratio of a circle'S circumference to its diameter.
52

5. Can you add sqrt 3 and sqrt 5?
C = (pi)d
70
No - only like radicals can be added.
53 - 59

6. 0^0
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Even
Undefined
67 - 71 - 73

7. Suppose that the graph of f(x) is the result of stretching y=x + 5 away from the x-axis by a factor of 2. What is the new equation for the graph f(x)?
y = (x + 5)/2
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
Relationship cannot be determined (what if x is negative?)
2sqrt6

8. What are 'Supplementary angles?'
A 30-60-90 triangle.
Two angles whose sum is 180.
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
Factors are few - multiples are many.

9. 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?
A chord is a line segment joining two points on a circle.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
48
4a^2(b)

10. 60 < all primes <70
61 - 67
11 - 13 - 17 - 19
4096
71 - 73 - 79

11. Legs 5 - 12. Hypotenuse?
Two angles whose sum is 180.
13
x= (1.2)(.8)lw
y = 2x^2 - 3

12. How to determine percent decrease?
2(pi)r^2 + 2(pi)rh
The point of intersection of the systems.
(amount of decrease/original price) x 100%
A = I (1 + rt)

13. To multiply a number by 10^x
(a - b)(a + b)
1:sqrt3:2
$3 -500 in the 9% and $2 -500 in the 7%.
Move the decimal point to the right x places

14. 7/8 in percent?
Pi is the ratio of a circle'S circumference to its diameter.
87.5%
From northeast - counterclockwise. I - II - III - IV
A reflection about the origin.

15. (-1)^3 =
F(x + c)
1
The direction of the inequality is reversed.
An arc is a portion of a circumference of a circle.

16. Max and Min lengths for a side of a triangle?
9 : 25
The third side is greater than the difference and less than the sum.
0
(a - b)(a + b)

17. What is the formula for compounded interest?
23 - 29
A set with a number of elements which can be counted.
Its last two digits are divisible by 4.
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.

18. What percent of 40 is 22?
55%
Two angles whose sum is 180.
No - only like radicals can be added.
Undefined

19. 413.03 x 10^(-4) =
413.03 / 10^4 (move the decimal point 4 places to the left)
9 : 25
288 (8 9 4)
Its divisible by 2 and by 3.

20. Which quadrant is the upper right hand?
52
I
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

21. What is the ratio of the surface area of a cube with an edge of 10 to the surface area of a rectangular solid with dimensions 2 - 4 - and 6?
9 & 6/7
1:1:sqrt2
75:11
y = 2x^2 - 3

22. A cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
1
5
The empty set - denoted by a circle with a diagonal through it.
I

23. Solve the quadratic equation ax^2 + bx + c= 0
Even
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
The shortest arc between points A and B on a circle'S diameter.
The objects within a set.

24. What is the set of elements found in both A and B?
Undefined - because we can'T divide by 0.
4:5
The interesection of A and B.
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)

25. Evaluate and write as a mixed number: 2/7 - 3/21 + 2 & 4/14
C = (pi)d
2 & 3/7
Undefined
Its last two digits are divisible by 4.

26. Legs: 3 - 4. Hypotenuse?
90 degrees
5
$11 -448
A reflection about the origin.

27. 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?
The sum of its digits is divisible by 3.
N! / (n-k)!
1:1:sqrt2
(n-2) x 180

28. a^2 - 2ab + b^2
7 / 1000
The point of intersection of the systems.
(a - b)^2
75:11

29. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
True
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)
13pi / 2
...multiply by 100.

30. 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
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
18
10
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]

31. What is the name for a grouping of the members within a set based on a shared characteristic?
Indeterminable.
2^9 / 2 = 256
A subset.
(a - b)(a + b)

32. To convert a percent to a fraction....
The second graph is less steep.
Divide by 100.
1:1:sqrt2
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).

33. Define a 'Term' -
Sector area = (n/360) X (pi)r^2
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)
12sqrt2
90

34. What is the surface area of a cylinder with radius 5 and height 8?
Undefined
130pi
16.6666%
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...

35. Evaluate 3& 2/7 / 1/3
x(x - y + 1)
1.0843 X 10^11
1/(x^y)
9 & 6/7

36. 5x^2 - 35x -55 = 0
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
Two angles whose sum is 90.
(a - b)^2
4a^2(b)

37. What is the graph of f(x) shifted downward c units or spaces?
1
F(x) - c
37.5%
2^9 / 2 = 256

38. Volume for a cylinder?
0
Area of the base X height = (pi)hr^2
Two angles whose sum is 180.
62.5%

39. 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?
Two equal sides and two equal angles.
2.592 kg
Part = Percent X Whole
6

40. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
An isosceles right triangle.
70
13
90pi

41. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
The curve opens upward and the vertex is the minimal point on the graph.
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
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}

42. What are the members or elements of a set?
All numbers multiples of 1.
The objects within a set.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
Lies opposite the greater angle

43. What is a finite set?
A set with a number of elements which can be counted.
Its negative reciprocal. (-b/a)
An angle which is supplementary to an interior angle.
F(x-c)

44. (-1)^2 =
1
x^(4+7) = x^11
The set of elements found in both A and B.
Part = Percent X Whole

45. 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?
500
9 : 25
10! / 3!(10-3)! = 120
A = pi(r^2)

46. Find the surface area of a cylinder with radius 3 and height 12.
90pi
441000 = 1 10 10 10 21 * 21
13
An expression with just one term (-6x - 2a^2)

47. What is the 'Range' of a series of numbers?
1
A set with no members - denoted by a circle with a diagonal through it.
The greatest value minus the smallest.
I

48. Length of an arc of a circle?
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)
The greatest value minus the smallest.
5
Angle/360 x 2(pi)r

49. 2sqrt4 + sqrt4 =
13pi / 2
3sqrt4
.0004809 X 10^11
Lies opposite the greater angle

50. How to find the circumference of a circle which circumscribes a square?
28. n = 8 - k = 2. n! / k!(n-k)!
The set of elements which can be found in either A or B.
A chord is a line segment joining two points on a circle.
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).