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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. 1/8 in percent?
Angle/360 x 2(pi)r
12.5%
A set with a number of elements which can be counted.
Diameter(Pi)

2. Solve the quadratic equation ax^2 + bx + c= 0
Move the decimal point to the right x places
4:5
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
5

3. Can the input value of a function have more than one output value (i.e. x: y - y1)?
(a + b)^2
No - the input value has exactly one output.
5 OR -5
All numbers multiples of 1.

4. How to determine percent decrease?
A = I (1 + rt)
(amount of decrease/original price) x 100%
41 - 43 - 47
1 & 37/132

5. What is the percent formula?
Part = Percent X Whole
20.5
The union of A and B.
1.0843 X 10^11

6. T or F? Given d -e &f =/ 0 - [(d^3)e(f^5)] / 2d(e^3) / [3(d^2)(e^3)(f^7)] / [6(e^5)(f^2)]?
Pi is the ratio of a circle'S circumference to its diameter.
True
Cd
F(x-c)

7. A cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
4.25 - 6 - 22
x^(6-3) = x^3
55%
1

8. What is the ratio of the sides of a 30-60-90 triangle?
1:sqrt3:2
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
(a + b)^2
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.

9. If an inequality is multiplied or divided by a negative number....
2^9 / 2 = 256
The direction of the inequality is reversed.
Move the decimal point to the right x places
10

10. What is an exterior angle?
6
12.5%
$11 -448
An angle which is supplementary to an interior angle.

11. 60 < all primes <70
C = 2(pi)r
55%
II
61 - 67

12. What is the graph of f(x) shifted downward c units or spaces?
An infinite set.
48
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
F(x) - c

13. 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?
2
3sqrt4
75:11
A chord is a line segment joining two points on a circle.

14. The four angles around a point measure y - 2y - 35 and 55 respectively. What is the value of y?
(a + b)^2
x= (1.2)(.8)lw
The overlapping sections.
90

15. What is the area of a regular hexagon with side 6?
The union of A and B.
3 - -3
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
The set of output values for a function.

16. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
An expression with just one term (-6x - 2a^2)
28. n = 8 - k = 2. n! / k!(n-k)!
A 30-60-90 triangle.

17. 8.84 / 5.2
1.7
Sector area = (n/360) X (pi)r^2
Pi is the ratio of a circle'S circumference to its diameter.
The longest arc between points A and B on a circle'S diameter.

18. What are complementary angles?
180
Two angles whose sum is 90.
A = pi(r^2)
(amount of increase/original price) x 100%

19. What is the 'union' of A and B?
Lies opposite the greater angle
Two equal sides and two equal angles.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
The set of elements which can be found in either A or B.

20. What is a parabola?
Ax^2 + bx + c where a -b and c are constants and a /=0
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.
2.592 kg
The third side is greater than the difference and less than the sum.

21. What is the sum of the angles of a triangle?
F(x) + c
180 degrees
13pi / 2
(n-2) x 180

22. x^2 = 9. What is the value of x?
3 - -3
72
Relationship cannot be determined (what if x is negative?)
1:sqrt3:2

23. 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
The union of A and B.
18
III
87.5%

24. 2sqrt4 + sqrt4 =
31 - 37
3sqrt4
10! / 3!(10-3)! = 120
When the function is not defined for all real numbers -; only a subset of the real numbers.

25. Which is greater? 64^5 or 16^8
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
I
III
180 degrees

26. 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?
5
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
62.5%
N! / (k!)(n-k)!

27. 40 < all primes<50
4096
41 - 43 - 47
C = (pi)d
No - only like radicals can be added.

28. Which quandrant is the lower right hand?
IV
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
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...
Infinite.

29. What is the 'Solution' for a set of inequalities.
The sum of digits is divisible by 9.
6 : 1 : 2
The overlapping sections.
.0004809 X 10^11

30. Area of a triangle?
Arc length = (n/360) x pi(2r) where n is the number of degrees.
(base*height) / 2
87.5%
No - only like radicals can be added.

31. What is it called when a point is reflected to the quadrant opposite it (i.e. I to III or II to IV)?
The curve opens upward and the vertex is the minimal point on the graph.
A reflection about the origin.
Angle/360 x 2(pi)r
18

32. 4.809 X 10^7 =
.0004809 X 10^11
y = (x + 5)/2
2sqrt6
9 & 6/7

33. Legs 5 - 12. Hypotenuse?
70
13
(p + q)/5
2^9 / 2 = 256

34. How to find the area of a sector?
Angle/360 x (pi)r^2
10
Indeterminable.
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.

35. 1/6 in percent?
(amount of decrease/original price) x 100%
The greatest value minus the smallest.
87.5%
16.6666%

36. What are 'Supplementary angles?'
27^(-4)
9 & 6/7
1
Two angles whose sum is 180.

37. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
1 & 37/132
... the square of the ratios of the corresponding sides.
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
12! / 5!7! = 792

38. What is the 'Solution' for a system of linear equations?
... the square of the ratios of the corresponding sides.
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
The point of intersection of the systems.
1/(x^y)

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?
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
2.592 kg
C = (pi)d
1:1:sqrt2

40. Can the output value of a function have more than one input value?
Two equal sides and two equal angles.
Arc length = (n/360) x pi(2r) where n is the number of degrees.
The shortest arc between points A and B on a circle'S diameter.
Yes. [i.e. f(x) = x^2 - 1

41. What is the absolute value function?
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Indeterminable.
G(x) = {x}
Members or elements

42. What is the side length of an equilateral triangle with altitude 6?
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...
F(x) - c
The second graph is less steep.
1/(x^y)

43. What is a central angle?
A chord is a line segment joining two points on a circle.
The direction of the inequality is reversed.
A central angle is an angle formed by 2 radii.
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

44. Reduce: 4.8 : 0.8 : 1.6
23 - 29
6 : 1 : 2
55%
An isosceles right triangle.

45. Order of quadrants:
An isosceles right triangle.
31 - 37
y = 2x^2 - 3
From northeast - counterclockwise. I - II - III - IV

46. Simplify the expression (p^2 - q^2)/ -5(q - p)
(p + q)/5
0
Angle/360 x 2(pi)r
Ax^2 + bx + c where a -b and c are constants and a /=0

47. Factor x^2 - xy + x.
Undefined
x(x - y + 1)
(p + q)/5
(12/2) x (sqrt15 / sqrt5) = 6sqrt3

48. What is the formula for computing simple interest?
3 - -3
A = I (1 + rt)
Infinite.
Ax^2 + bx + c where a -b and c are constants and a /=0

49. A number is divisible by 6 if...
... the square of the ratios of the corresponding sides.
90
Its divisible by 2 and by 3.
An angle which is supplementary to an interior angle.

50. A number is divisible by 4 is...
28. n = 8 - k = 2. n! / k!(n-k)!
1:sqrt3:2
Diameter(Pi)
Its last two digits are divisible by 4.