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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. 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?
x= (1.2)(.8)lw
2.592 kg
An arc is a portion of a circumference 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)

2. Write 10 -843 X 10^7 in scientific notation
A = pi(r^2)
1.0843 X 10^11
An infinite set.
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. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
Even
18
3
A central angle is an angle formed by 2 radii.

4. 5/6 in percent?
1
83.333%
(a - b)^2
From northeast - counterclockwise. I - II - III - IV

5. What is the sum of the angles of a triangle?
A 30-60-90 triangle.
3
The two xes after factoring.
180 degrees

6. Whats the difference between factors and multiples?
1
Members or elements
(amount of decrease/original price) x 100%
Factors are few - multiples are many.

7. Formula to find a circle'S circumference from its radius?
C = 2(pi)r
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
10
3/2 - 5/3

8. What is an isoceles triangle?
67 - 71 - 73
Two equal sides and two equal angles.
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
18

9. What is the measure of an exterior angle of a regular pentagon?
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
288 (8 9 4)
72
(a - b)^2

10. Evaluate 3& 2/7 / 1/3
1
Members or elements
9 & 6/7
1

11. What are the integers?
12.5%
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
A circle centered on the origin with radius 8.
All numbers multiples of 1.

12. Suppose that the graph of f(x) is the result of sliding the graph of y=2x^2 down 3 units of spaces. What is the new equation?
41 - 43 - 47
y = 2x^2 - 3
28. n = 8 - k = 2. n! / k!(n-k)!
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16

13. What is the 'Range' of a series of numbers?
The greatest value minus the smallest.
12! / 5!7! = 792
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
Undefined

14. Can you add sqrt 3 and sqrt 5?
An arc is a portion of a circumference of a circle.
Triangles with same measure and same side lengths.
1.0843 X 10^11
No - only like radicals can be added.

15. Define an 'expression'.
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)
All numbers multiples of 1.
A circle centered at -2 - -2 with radius 3.
5 OR -5

16. Which is greater? 200x^295 or 10x^294?
A central angle is an angle formed by 2 radii.
6
Relationship cannot be determined (what if x is negative?)
Two angles whose sum is 90.

17. Find the surface area of a cylinder with radius 3 and height 12.
288 (8 9 4)
31 - 37
Angle/360 x 2(pi)r
90pi

18. There are 10 finalists for the school spelling bee. A first - second - and third place trophy will be awarded. How many different people can get the three prizes?
10! / 3!(10-3)! = 120
The second graph is less steep.
37.5%
6

19. 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?
(base*height) / 2
Part = Percent X Whole
1 & 37/132
48

20. 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?
4a^2(b)
N! / (k!)(n-k)!
(n-2) x 180
1:sqrt3:2

21. Circumference of a circle?
A circle centered at -2 - -2 with radius 3.
... the square of the ratios of the corresponding sides.
(amount of increase/original price) x 100%
Diameter(Pi)

22. 6w^2 - w - 15 = 0
1
Diameter(Pi)
Its negative reciprocal. (-b/a)
3/2 - 5/3

23. Length of an arc of a circle?
83.333%
F(x) + c
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
Angle/360 x 2(pi)r

24. How many sides does a hexagon have?
An expression with just one term (-6x - 2a^2)
1
6
When the function is not defined for all real numbers -; only a subset of the real numbers.

25. 7/8 in percent?
2 & 3/7
87.5%
288 (8 9 4)
An expression with just one term (-6x - 2a^2)

26. A cylinder has a surface area of 22pi. If the cylinder has a height of 10 - what is the radius?
1
IV
7 / 1000
The shortest arc between points A and B on a circle'S diameter.

27. What is a chord of a circle?
Diameter(Pi)
A chord is a line segment joining two points on a circle.
413.03 / 10^4 (move the decimal point 4 places to the left)
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

28. What is the name of set with a number of elements which cannot be counted?
5 OR -5
An infinite set.
II
13

29. A number is divisible by 3 if ...
(n-2) x 180
0
Triangles with same measure and same side lengths.
The sum of its digits is divisible by 3.

30. Describe the relationship between 3x^2 and 3(x - 1)^2
(a - b)(a + b)
F(x + c)
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
1/(x^y)

31. What is the 'Solution' for a set of inequalities.
.0004809 X 10^11
The overlapping sections.
$11 -448
x^(2(4)) =x^8 = (x^4)^2

32. What are the smallest three prime numbers greater than 65?
2 & 3/7
1
The sum of its digits is divisible by 3.
67 - 71 - 73

33. When the 'a' in a parabola is positive....
1/2 times 7/3
Move the decimal point to the right x places
18
The curve opens upward and the vertex is the minimal point on the graph.

34. What is the 'Range' of a function?
An infinite set.
Indeterminable.
12! / 5!7! = 792
The set of output values for a function.

35. What is the set of elements found in both A and B?
0
413.03 / 10^4 (move the decimal point 4 places to the left)
The interesection of A and B.
x^(2(4)) =x^8 = (x^4)^2

36. Evaluate (4^3)^2
A = I (1 + rt)
Ax^2 + bx + c where a -b and c are constants and a /=0
4096
Cd

37. What is the intersection of A and B?
x^(4+7) = x^11
Factors are few - multiples are many.
2
The set of elements found in both A and B.

38. 5x^2 - 35x -55 = 0
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
y = (x + 5)/2
48
The point of intersection of the systems.

39. 5/8 in percent?
62.5%
9 & 6/7
1
Sector area = (n/360) X (pi)r^2

40. Factor a^2 + 2ab + b^2
41 - 43 - 47
6 : 1 : 2
Two angles whose sum is 180.
(a + b)^2

41. What are the rational numbers?
An angle which is supplementary to an interior angle.
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
Members or elements
1:sqrt3:2

42. What is the area of a regular hexagon with side 6?
6
(a - b)(a + b)
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
.0004809 X 10^11

43. In a regular polygon with n sides - the formula for the sum of interior angles
72
1
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
(n-2) x 180

44. Simplify the expression (p^2 - q^2)/ -5(q - p)
288 (8 9 4)
2 & 3/7
(p + q)/5
I

45. a^2 - b^2
(a - b)(a + b)
A reflection about the axis.
1/2 times 7/3
70

46. Nine coins are tossed simultaneously. In how many of the outcomes will the fourth coin tossed show heads?
Triangles with same measure and same side lengths.
41 - 43 - 47
The interesection of A and B.
2^9 / 2 = 256

47. The objects in a set are called two names:
x(x - y + 1)
Members or elements
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
Ax^2 + bx + c where a -b and c are constants and a /=0

48. How to find the area of a sector?
Angle/360 x (pi)r^2
$11 -448
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.

49. The four angles around a point measure y - 2y - 35 and 55 respectively. What is the value of y?
90
(a + b)^2
Cd
1:1:sqrt2

50. What is a central angle?
The third side is greater than the difference and less than the sum.
6
C = (pi)d
A central angle is an angle formed by 2 radii.