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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. What is the measure of an exterior angle of a regular pentagon?
90 degrees
F(x) - c
72
2^9 / 2 = 256

2. The ratio of the areas of two similar polygons is ...
4:5
True
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
... the square of the ratios of the corresponding sides.

3. Describe the relationship between 3x^2 and 3(x - 1)^2
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
Move the decimal point to the right x places
An infinite set.
12! / 5!7! = 792

4. Evaluate 3& 2/7 / 1/3
9 & 6/7
37.5%
(n-2) x 180
The second graph is less steep.

5. Surface area for a cylinder?
28. n = 8 - k = 2. n! / k!(n-k)!
2(pi)r^2 + 2(pi)rh
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

6. 4.809 X 10^7 =
The shortest arc between points A and B on a circle'S diameter.
An expression with just one term (-6x - 2a^2)
90
.0004809 X 10^11

7. When the 'a' in the parabola is negative...
Move the decimal point to the right x places
20.5
The curve opens downward and the vertex is the maximum point on the graph.
The set of elements which can be found in either A or B.

8. If r - t - s & u are distinct - consecutive prime numbers - less than 31 - which of the following could be an average of them (4 - 4.25 - 6 - 9 - 24 - 22 - 24)
4.25 - 6 - 22
x(x - y + 1)
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...
2.592 kg

9. A cylinder has a surface area of 22pi. If the cylinder has a height of 10 - what is the radius?
1
Angle/360 x 2(pi)r
C = (pi)d
A reflection about the origin.

10. Write 10 -843 X 10^7 in scientific notation
The union of A and B.
6 : 1 : 2
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
1.0843 X 10^11

11. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
4:5
10! / (10-3)! = 720
3/2 - 5/3
x(x - y + 1)

12. Can you subtract 3sqrt4 from sqrt4?
(a - b)(a + b)
(amount of decrease/original price) x 100%
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
Yes - like radicals can be added/subtracted.

13. The four angles around a point measure y - 2y - 35 and 55 respectively. What is the value of y?
2sqrt6
90
The two xes after factoring.
9 : 25

14. What is the intersection of A and B?
The set of elements found in both A and B.
1
(amount of increase/original price) x 100%
90 degrees

15. What is the third quartile of the following data set: 44 - 58 - 63 - 63 - 68 - 70 - 82
The sum of digits is divisible by 9.
A chord is a line segment joining two points on a circle.
Yes - like radicals can be added/subtracted.
70

16. 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?
20.5
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
N! / (k!)(n-k)!

17. Can the input value of a function have more than one output value (i.e. x: y - y1)?
Arc length = (n/360) x pi(2r) where n is the number of degrees.
413.03 / 10^4 (move the decimal point 4 places to the left)
No - the input value has exactly one output.
Triangles with same measure and same side lengths.

18. Define a 'monomial'
Its negative reciprocal. (-b/a)
The set of output values for a function.
An expression with just one term (-6x - 2a^2)
10! / 3!(10-3)! = 120

19. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
4725
441000 = 1 10 10 10 21 * 21
2
When the function is not defined for all real numbers -; only a subset of the real numbers.

20. Formula for the area of a sector of a circle?
Sector area = (n/360) X (pi)r^2
F(x) + c
The greatest value minus the smallest.
x^(2(4)) =x^8 = (x^4)^2

21. a^2 - 2ab + b^2
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
3sqrt4
(a - b)^2
5 OR -5

22. Formula for the area of a circle?
8
A = pi(r^2)
A 30-60-90 triangle.
(a + b)^2

23. What are the irrational numbers?

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24. 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?
1
87.5%
Its divisible by 2 and by 3.
10! / 3!(10-3)! = 120

25. What is a central angle?
A central angle is an angle formed by 2 radii.
N! / (n-k)!
An isosceles right triangle.
An infinite set.

26. What are the rational numbers?
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
Sector area = (n/360) X (pi)r^2
The second graph is less steep.
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.

27. 40 < all primes<50
N! / (k!)(n-k)!
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
The steeper the slope.
41 - 43 - 47

28. What are the integers?
The curve opens downward and the vertex is the maximum point on the graph.
The union of A and B.
All numbers multiples of 1.
441000 = 1 10 10 10 21 * 21

29. Evaluate and write as a mixed number: 2/7 - 3/21 + 2 & 4/14
75:11
2 & 3/7
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
55%

30. 60 < all primes <70
61 - 67
The overlapping sections.
A chord is a line segment joining two points on a circle.
1/(x^y)

31. What is the order of operations?
The shortest arc between points A and B on a circle'S diameter.
The greatest value minus the smallest.
When the function is not defined for all real numbers -; only a subset of the real numbers.
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)

32. 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?
An expression with just one term (-6x - 2a^2)
3 - -3
48
Members or elements

33. Legs 5 - 12. Hypotenuse?
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.
13
2sqrt6

34. Simplify the expression (p^2 - q^2)/ -5(q - p)
(p + q)/5
Triangles with same measure and same side lengths.
Two angles whose sum is 90.
The curve opens upward and the vertex is the minimal point on the graph.

35. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
y = 2x^2 - 3
... the square of the ratios of the corresponding sides.
Yes. [i.e. f(x) = x^2 - 1
A 30-60-90 triangle.

36. A number is divisible by 6 if...
1
Its divisible by 2 and by 3.
1:1:sqrt2
180

37. Length of an arc of a circle?
y = 2x^2 - 3
1.7
The sum of its digits is divisible by 3.
Angle/360 x 2(pi)r

38. Max and Min lengths for a side of a triangle?
A set with a number of elements which can be counted.
5
The third side is greater than the difference and less than the sum.
Two angles whose sum is 180.

39. What is the ratio of the sides of an isosceles right triangle?
1:1:sqrt2
IV
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
A central angle is an angle formed by 2 radii.

40. What is a finite set?
18
90
13pi / 2
A set with a number of elements which can be counted.

41. What are the real numbers?
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! / 5!7! = 792
N! / (n-k)!
Undefined

42. What is the area of a regular hexagon with side 6?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
Cd
y = 2x^2 - 3
9 & 6/7

43. What is the 'Solution' for a system of linear equations?
8
y = (x + 5)/2
The point of intersection of the systems.
An isosceles right triangle.

44. x^4 + x^7 =
4.25 - 6 - 22
1
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
x^(4+7) = x^11

45. What is the graph of f(x) shifted left c units or spaces?
62.5%
A 30-60-90 triangle.
F(x + c)
An arc is a portion of a circumference of a circle.

46. Legs 6 - 8. Hypotenuse?
71 - 73 - 79
31 - 37
Yes - like radicals can be added/subtracted.
10

47. When the 'a' in a parabola is positive....
1
70
The curve opens upward and the vertex is the minimal point on the graph.
7 / 1000

48. What are the smallest three prime numbers greater than 65?
Yes - like radicals can be added/subtracted.
41 - 43 - 47
1:sqrt3:2
67 - 71 - 73

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?
4.25 - 6 - 22
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
An isosceles right triangle.
The sum of its digits is divisible by 3.

50. 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
N! / (n-k)!
18
2.592 kg
Divide by 100.