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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. How to find the area of a sector?
90 degrees
Angle/360 x (pi)r^2
x^(6-3) = x^3
Infinite.

2. Whats the difference between factors and multiples?
Factors are few - multiples are many.
3
1.0843 X 10^11
0

3. P and r are factors of 100. What is greater - pr or 100?
No - only like radicals can be added.
71 - 73 - 79
Indeterminable.
12! / 5!7! = 792

4. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
3
12! / 5!7! = 792
Its divisible by 2 and by 3.
16.6666%

5. Order of quadrants:
An arc is a portion of a circumference of a circle.
83.333%
(a + b)^2
From northeast - counterclockwise. I - II - III - IV

6. Define a 'Term' -
11 - 13 - 17 - 19
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)
27^(-4)
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.

7. What is the order of operations?
8
180
1
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)

8. 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
2 & 3/7
(a + b)^2
8
18

9. What is the set of elements which can be found in either A or B?
1
The sum of digits is divisible by 9.
31 - 37
The union of A and B.

10. What is the coefficient of the x^2 term in the product of (x + 1)(x + 2)(x -1)?
(a - b)^2
10
2
13

11. Is 0 even or odd?
A circle centered on the origin with radius 8.
Even
6
From northeast - counterclockwise. I - II - III - IV

12. Legs 5 - 12. Hypotenuse?
y = (x + 5)/2
13
An infinite set.
The greatest value minus the smallest.

13. 7/8 in percent?
8
87.5%
3/2 - 5/3
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...

14. What is it called when a point is reflected to the quadrant opposite it (i.e. I to III or II to IV)?
The overlapping sections.
An expression with just one term (-6x - 2a^2)
A reflection about the origin.
F(x-c)

15. sqrt 2(sqrt 6)=
5
From northeast - counterclockwise. I - II - III - IV
Sqrt 12
Yes. [i.e. f(x) = x^2 - 1

16. What is an exterior angle?
An angle which is supplementary to an interior angle.
Sqrt 12
The second graph is less steep.
1:sqrt3:2

17. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
1/2 times 7/3
An isosceles right triangle.
F(x + c)
288 (8 9 4)

18. What is the percent formula?
Part = Percent X Whole
62.5%
The steeper the slope.
41 - 43 - 47

19. Can the output value of a function have more than one input value?
Yes. [i.e. f(x) = x^2 - 1
62.5%
A reflection about the axis.
(p + q)/5

20. If the two sides of a triangle are unequal then the longer side...
Lies opposite the greater angle
x(x - y + 1)
13pi / 2
Infinite.

21. Can you add sqrt 3 and sqrt 5?
52
No - only like radicals can be added.
A circle centered at -2 - -2 with radius 3.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

22. A number is divisible by 4 is...
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
The union of A and B.
Its last two digits are divisible by 4.
Yes. [i.e. f(x) = x^2 - 1

23. Length of an arc of a circle?
12! / 5!7! = 792
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
Angle/360 x 2(pi)r
Diameter(Pi)

24. a^2 - b^2
A set with no members - denoted by a circle with a diagonal through it.
II
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
(a - b)(a + b)

25. Simplify 4sqrt21 X 5sqrt2 / 10sqrt7
(amount of decrease/original price) x 100%
2sqrt6
Undefined
The set of elements found in both A and B.

26. Find the surface area of a cylinder with radius 3 and height 12.
90pi
A = pi(r^2)
2(pi)r^2 + 2(pi)rh
A set with no members - denoted by a circle with a diagonal through it.

27. x^6 / x^3
x^(6-3) = x^3
The curve opens upward and the vertex is the minimal point on the graph.
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)
...multiply by 100.

28. What percent of 40 is 22?
F(x + c)
20.5
2sqrt6
55%

29. Simplify the expression [(b^2 - c^2) / (b - c)]
The steeper the slope.
(b + c)
75:11
20.5

30. What are complementary angles?
Factors are few - multiples are many.
(a + b)^2
The two xes after factoring.
Two angles whose sum is 90.

31. When the 'a' in a parabola is positive....
55%
The curve opens upward and the vertex is the minimal point on the graph.
1:sqrt3:2
A set with no members - denoted by a circle with a diagonal through it.

32. a^2 + 2ab + b^2
The set of elements which can be found in either A or B.
(a + b)^2
2
1

33. What are the members or elements of a set?
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
The objects within a set.
(p + q)/5
An angle which is supplementary to an interior angle.

34. 40 < all primes<50
41 - 43 - 47
A = I (1 + rt)
Area of the base X height = (pi)hr^2
(12/2) x (sqrt15 / sqrt5) = 6sqrt3

35. 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?
9 : 25
A reflection about the origin.
10! / (10-3)! = 720
(p + q)/5

36. Legs: 3 - 4. Hypotenuse?
1 & 37/132
I
5
Sqrt 12

37. What is the formula for compounded interest?
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
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.
Its divisible by 2 and by 3.
Its last two digits are divisible by 4.

38. A number is divisible by 9 if...
4:5
x= (1.2)(.8)lw
3
The sum of digits is divisible by 9.

39. 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.
90 degrees
A reflection about the axis.
9 & 6/7
x= (1.2)(.8)lw

40. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
Part = Percent X Whole
4:5
Pi is the ratio of a circle'S circumference to its diameter.
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

41. 0^0
A circle centered at -2 - -2 with radius 3.
II
130pi
Undefined

42. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
11 - 13 - 17 - 19
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
28. n = 8 - k = 2. n! / k!(n-k)!
8

43. (6sqrt3) x (2sqrt5) =
37.5%
8
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
y = (x + 5)/2

44. What is a major arc?

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45. Formula for the area of a sector of a circle?
Sector area = (n/360) X (pi)r^2
6
Undefined - because we can'T divide by 0.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

46. What is a central angle?
C = 2(pi)r
(amount of decrease/original price) x 100%
A central angle is an angle formed by 2 radii.
1

47. 5/6 in percent?
83.333%
(a - b)^2
1 & 37/132
The shortest arc between points A and B on a circle'S diameter.

48. The perimeter of a square is 48 inches. The length of its diagonal is:
12sqrt2
70
1
.0004809 X 10^11

49. 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?
Yes. [i.e. f(x) = x^2 - 1
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
Triangles with same measure and same side lengths.
The longest arc between points A and B on a circle'S diameter.

50. The larger the absolute value of the slope...
The steeper the slope.
90pi
71 - 73 - 79
28. n = 8 - k = 2. n! / k!(n-k)!