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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. 1/6 in percent?
The steeper the slope.
16.6666%
37.5%
From northeast - counterclockwise. I - II - III - IV

2. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
1.0843 X 10^11
13pi / 2
...multiply by 100.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15

3. Can you subtract 3sqrt4 from sqrt4?
Members or elements
Yes - like radicals can be added/subtracted.
Diameter(Pi)
1

4. There are 10 finalists for the school spelling bee. A first - second - and third place trophy will be awarded. In how many ways can the judges award the 3 prizes?
10! / (10-3)! = 720
288 (8 9 4)
70
10! / 3!(10-3)! = 120

5. 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?
1
180
N! / (k!)(n-k)!
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.

6. What does the graph x^2 + y^2 = 64 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)
The set of elements found in both A and B.
A circle centered on the origin with radius 8.
1

7. Formula to find a circle'S circumference from its radius?
180 degrees
C = 2(pi)r
(a - b)(a + b)
441000 = 1 10 10 10 21 * 21

8. What is the surface area of a cylinder with radius 5 and height 8?
130pi
Its negative reciprocal. (-b/a)
27^(-4)
16.6666%

9. sqrt 2(sqrt 6)=
Sqrt 12
A subset.
Undefined
The set of elements found in both A and B.

10. What is the name for a grouping of the members within a set based on a shared characteristic?
A subset.
All numbers multiples of 1.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
N! / (n-k)!

11. Define a 'Term' -
(a - b)(a + b)
288 (8 9 4)
1
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 an arc of a circle?
All numbers multiples of 1.
No - only like radicals can be added.
The empty set - denoted by a circle with a diagonal through it.
An arc is a portion of a circumference of a circle.

13. The slope of a line perpendicular to (a/b)?
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Its negative reciprocal. (-b/a)
4725
2

14. Solve the quadratic equation ax^2 + bx + c= 0
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
130pi
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)

15. How many 3-digit positive integers are even and do not contain the digit 4?
x(x - y + 1)
288 (8 9 4)
1/(x^y)
F(x) - c

16. 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?
4.25 - 6 - 22
2.592 kg
4a^2(b)
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

17. Factor a^2 + 2ab + b^2
(a + b)^2
(amount of decrease/original price) x 100%
1/a^6
23 - 29

18. What is the 'domain' of a function?
The set of input values for a function.
$11 -448
Cd
F(x + c)

19. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
x^(4+7) = x^11
62.5%
Sector area = (n/360) X (pi)r^2
A circle centered at -2 - -2 with radius 3.

20. What is the 'Range' of a series of numbers?
1
The greatest value minus the smallest.
3 - -3
0

21. What is a finite set?
55%
Cd
A set with a number of elements which can be counted.
Part = Percent X Whole

22. 5/8 in percent?
The set of elements found in both A and B.
(a - b)(a + b)
62.5%
A reflection about the axis.

23. Factor x^2 - xy + x.
The set of elements which can be found in either A or 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)
x(x - y + 1)
12sqrt2

24. Can the input value of a function have more than one output value (i.e. x: y - y1)?
61 - 67
4a^2(b)
N! / (n-k)!
No - the input value has exactly one output.

25. What is the ratio of the sides of an isosceles right triangle?
Two angles whose sum is 90.
The steeper the slope.
1:1:sqrt2
The direction of the inequality is reversed.

26. Legs: 3 - 4. Hypotenuse?
4a^2(b)
5
A 30-60-90 triangle.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

27. 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?
4096
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
6
A tangent is a line that only touches one point on the circumference of a circle.

28. 25^(1/2) or sqrt. 25 =
5 OR -5
71 - 73 - 79
10
y = 2x^2 - 3

29. 1/8 in percent?
(b + c)
12.5%
41 - 43 - 47
441000 = 1 10 10 10 21 * 21

30. Describe the relationship between the graphs of x^2 and (1/2)x^2
A subset.
x^(6-3) = x^3
1:sqrt3:2
The second graph is less steep.

31. A number is divisible by 9 if...
8
13
The sum of digits is divisible by 9.
9 : 25

32. What is the name of set with a number of elements which cannot be counted?
An infinite set.
87.5%
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
True

33. Pi is a ratio of what to what?

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34. Which quadrant is the lower left hand?
III
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
441000 = 1 10 10 10 21 * 21
C = 2(pi)r

35. What is a minor arc?

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36. 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?
...multiply by 100.
y = (x + 5)/2
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
75:11

37. A number is divisible by 3 if ...
16.6666%
Its negative reciprocal. (-b/a)
The sum of its digits is divisible by 3.
13

38. 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
An arc is a portion of a circumference of a circle.
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
Triangles with same measure and same side lengths.

39. How to determine percent decrease?
An arc is a portion of a circumference of a circle.
(amount of decrease/original price) x 100%
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
Ax^2 + bx + c where a -b and c are constants and a /=0

40. (6sqrt3) x (2sqrt5) =
288 (8 9 4)
4:5
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
180 degrees

41. Simplify 9^(1/2) X 4^3 X 2^(-6)?
II
3
90 degrees
The direction of the inequality is reversed.

42. 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?
0
500
5
53 - 59

43. What are the irrational numbers?

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44. What is the formula for compounded interest?
1
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.
5 OR -5
1

45. What number between 70 & 75 - inclusive - has the greatest number of factors?
$11 -448
The curve opens downward and the vertex is the maximum point on the graph.
Factors are few - multiples are many.
72

46. Which quadrant is the upper right hand?
F(x) - c
... the square of the ratios of the corresponding sides.
An arc is a portion of a circumference of a circle.
I

47. To convert a percent to a fraction....
Divide by 100.
Triangles with same measure and same side lengths.
Indeterminable.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

48. Circumference of a circle?
4a^2(b)
An infinite set.
Sector area = (n/360) X (pi)r^2
Diameter(Pi)

49. What is the slope of a horizontal line?
From northeast - counterclockwise. I - II - III - IV
0
Undefined
2

50. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
A 30-60-90 triangle.
An isosceles right triangle.
Diameter(Pi)
Arc length = (n/360) x pi(2r) where n is the number of degrees.