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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. Convert 0.7% to a fraction.
Undefined - because we can'T divide by 0.
G(x) = {x}
7 / 1000
3

2. For similar triangles - the ratio of their corresponding sides is 2:3. What is the ratio of their areas?
1
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Two angles whose sum is 180.
Lies opposite the greater angle

3. What is the third quartile of the following data set: 44 - 58 - 63 - 63 - 68 - 70 - 82
70
13
90 degrees
Pi is the ratio of a circle'S circumference to its diameter.

4. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
4:5
F(x) + c
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
Divide by 100.

5. 20<all primes<30
23 - 29
441000 = 1 10 10 10 21 * 21
x^(4+7) = x^11
12! / 5!7! = 792

6. x^6 / x^3
x^(6-3) = x^3
.0004809 X 10^11
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
II

7. 1/8 in percent?
12.5%
A circle centered at -2 - -2 with radius 3.
3
Yes. [i.e. f(x) = x^2 - 1

8. What number between 70 & 75 - inclusive - has the greatest number of factors?
5
N! / (n-k)!
72
The set of output values for a function.

9. Can you add sqrt 3 and sqrt 5?
No - only like radicals can be added.
6
(a - b)^2
A central angle is an angle formed by 2 radii.

10. What is a parabola?
The second graph is less steep.
Ax^2 + bx + c where a -b and c are constants and a /=0
The third side is greater than the difference and less than the sum.
90

11. Can the output value of a function have more than one input value?
500
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
Yes. [i.e. f(x) = x^2 - 1
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)

12. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
Cd
The direction of the inequality is reversed.
441000 = 1 10 10 10 21 * 21
III

13. 70 < all primes< 80
71 - 73 - 79
4:5
(p + q)/5
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.

14. What is an isoceles triangle?
A reflection about the axis.
10! / 3!(10-3)! = 120
Two equal sides and two equal angles.
Arc length = (n/360) x pi(2r) where n is the number of degrees.

15. 4.809 X 10^7 =
The point of intersection of the systems.
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
N! / (k!)(n-k)!
.0004809 X 10^11

16. What is the ratio of the sides of an isosceles right triangle?
The set of elements which can be found in either A or B.
1:1:sqrt2
83.333%
No - the input value has exactly one output.

17. Which quandrant is the lower right hand?
IV
x^(4+7) = x^11
No - only like radicals can be added.
(amount of increase/original price) x 100%

18. 5x^2 - 35x -55 = 0
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
4725
F(x-c)
A tangent is a line that only touches one point on the circumference of a circle.

19. What are complementary angles?
(amount of decrease/original price) x 100%
Two angles whose sum is 90.
The two xes after factoring.
48

20. What is the slope of a horizontal line?
0
8
23 - 29
Infinite.

21. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
A 30-60-90 triangle.
The two xes after factoring.
4:5
62.5%

22. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
A reflection about the axis.
C = 2(pi)r
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
13

23. How many multiples does a given number have?
Infinite.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
10
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.

24. 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?
62.5%
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
(a + b)^2
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

25. 5/8 in percent?
441000 = 1 10 10 10 21 * 21
The longest arc between points A and B on a circle'S diameter.
3 - -3
62.5%

26. Which quadrant is the lower left hand?
No - only like radicals can be added.
The curve opens upward and the vertex is the minimal point on the graph.
1.0843 X 10^11
III

27. If the two sides of a triangle are unequal then the longer side...
31 - 37
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
Lies opposite the greater angle
(12/2) x (sqrt15 / sqrt5) = 6sqrt3

28. Evaluate and write as a mixed number: 2/7 - 3/21 + 2 & 4/14
180
A subset.
2 & 3/7
(a - b)(a + b)

29. What is the 'Solution' for a set of inequalities.
Members or elements
1
... the square of the ratios of the corresponding sides.
The overlapping sections.

30. What is the 'domain' of a function?
y = 2x^2 - 3
The set of input values for a function.
1
1/(x^y)

31. 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?
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
Factors are few - multiples are many.
1/2 times 7/3
N! / (n-k)!

32. What is an exterior angle?
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
A set with a number of elements which can be counted.
The steeper the slope.
An angle which is supplementary to an interior angle.

33. What is the name of set with a number of elements which cannot be counted?
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)
4.25 - 6 - 22
3
An infinite set.

34. 30< all primes<40
C = (pi)d
75:11
31 - 37
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

35. What is a central angle?
The objects within a set.
Infinite.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
A central angle is an angle formed by 2 radii.

36. A number is divisible by 9 if...
Indeterminable.
(b + c)
The sum of digits is divisible by 9.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

37. What is the ratio of the sides of a 30-60-90 triangle?
83.333%
1:sqrt3:2
1
2sqrt6

38. sqrt 2(sqrt 6)=
Sqrt 12
87.5%
1
1/(x^y)

39. What are the roots of the quadrinomial x^2 + 2x + 1?
72
The interesection of A and B.
Ax^2 + bx + c where a -b and c are constants and a /=0
The two xes after factoring.

40. P and r are factors of 100. What is greater - pr or 100?
500
41 - 43 - 47
Indeterminable.
Factors are few - multiples are many.

41. What percent of 40 is 22?
y = (x + 5)/2
55%
180
1

42. Describe the relationship between the graphs of x^2 and (1/2)x^2
F(x-c)
An expression with just one term (-6x - 2a^2)
The second graph is less steep.
2sqrt6

43. What is the graph of f(x) shifted upward c units or spaces?
F(x) + c
48
A tangent is a line that only touches one point on the circumference of a circle.
A central angle is an angle formed by 2 radii.

44. What is the formula for computing simple interest?
2sqrt6
12sqrt2
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)
A = I (1 + rt)

45. 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?
Even
2sqrt6
67 - 71 - 73
N! / (k!)(n-k)!

46. What is the set of elements which can be found in either A or B?
1
The union of A and B.
12! / 5!7! = 792
(12/2) x (sqrt15 / sqrt5) = 6sqrt3

47. How to determine percent increase?
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
1.0843 X 10^11
A = pi(r^2)
(amount of increase/original price) x 100%

48. What is the empty set?
A set with no members - denoted by a circle with a diagonal through it.
0
20.5
F(x-c)

49. Surface area for a cylinder?
2(pi)r^2 + 2(pi)rh
3
y = 2x^2 - 3
x(x - y + 1)

50. 50 < all primes< 60
C = (pi)d
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
53 - 59
2^9 / 2 = 256