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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. The ratio of the areas of two similar polygons is ...
... the square of the ratios of the corresponding sides.
Divide by 100.
1/a^6
Relationship cannot be determined (what if x is negative?)

2. a^0 =
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
1 & 37/132
II
1

3. How to find the diagonal of a rectangular solid?
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
2
2 & 3/7
72

4. What is a chord of a circle?
The curve opens downward and the vertex is the maximum point on the graph.
83.333%
12.5%
A chord is a line segment joining two points on a circle.

5. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
.0004809 X 10^11
Undefined
4:5
13pi / 2

6. a^2 - b^2
13pi / 2
The set of input values for a function.
(a - b)(a + b)
288 (8 9 4)

7. 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
All numbers multiples of 1.
A set with no members - denoted by a circle with a diagonal through it.
F(x) - c
18

8. How to determine percent decrease?
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
An infinite set.
(amount of decrease/original price) x 100%
II

9. 10<all primes<20
83.333%
11 - 13 - 17 - 19
A set with a number of elements which can be counted.
The curve opens downward and the vertex is the maximum point on the graph.

10. What is the intersection of A and B?
The set of output values for a function.
90 degrees
The set of elements found in both A and B.
67 - 71 - 73

11. 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?
180
Two angles whose sum is 90.
72
10! / 3!(10-3)! = 120

12. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
A grouping of the members within a set based on a shared characteristic.
0
3
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)

13. What is the area of a regular hexagon with side 6?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
y = 2x^2 - 3
N! / (n-k)!
41 - 43 - 47

14. What are the real numbers?
3sqrt4
18
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)
x^(6-3) = x^3

15. Can the input value of a function have more than one output value (i.e. x: y - y1)?
11 - 13 - 17 - 19
A = pi(r^2)
An infinite set.
No - the input value has exactly one output.

16. 40 < all primes<50
41 - 43 - 47
55%
...multiply by 100.
An isosceles right triangle.

17. A number is divisible by 9 if...
The sum of digits is divisible by 9.
The overlapping sections.
90
1

18. What is the graph of f(x) shifted upward c units or spaces?
All numbers multiples of 1.
(amount of increase/original price) x 100%
The set of elements found in both A and B.
F(x) + c

19. 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?
Its divisible by 2 and by 3.
F(x) + c
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
500

20. Circumference of a circle?
Diameter(Pi)
F(x) + c
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
(a - b)^2

21. Legs: 3 - 4. Hypotenuse?
23 - 29
5
1
52

22. What is the 'Solution' for a system of linear equations?
The third side is greater than the difference and less than the sum.
The interesection of A and B.
The set of elements found in both A and B.
The point of intersection of the systems.

23. What is the ratio of the sides of a 30-60-90 triangle?
The point of intersection of the systems.
...multiply by 100.
1:sqrt3:2
6 : 1 : 2

24. x^(-y)=
1/(x^y)
27^(-4)
1
... the square of the ratios of the corresponding sides.

25. What is a parabola?
1
No - only like radicals can be added.
Ax^2 + bx + c where a -b and c are constants and a /=0
Diameter(Pi)

26. What is the 'Solution' for a set of inequalities.
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
6 : 1 : 2
The overlapping sections.
y = 2x^2 - 3

27. A number is divisible by 6 if...
(base*height) / 2
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
Its divisible by 2 and by 3.
An expression with just one term (-6x - 2a^2)

28. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
An isosceles right triangle.
2 & 3/7
31 - 37
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

29. To convert a percent to a fraction....
1:sqrt3:2
Members or elements
Angle/360 x (pi)r^2
Divide by 100.

30. 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?
180 degrees
x= (1.2)(.8)lw
48
72

31. Max and Min lengths for a side of a triangle?
90pi
The third side is greater than the difference and less than the sum.
55%
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

32. Simplify (a^2 + b)^2 - (a^2 - b)^2
1
4a^2(b)
1
A chord is a line segment joining two points on a circle.

33. (6sqrt3) x (2sqrt5) =
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
x= (1.2)(.8)lw
Angle/360 x (pi)r^2

34. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
62.5%
A 30-60-90 triangle.
7 / 1000
C = 2(pi)r

35. Evaluate and write as a mixed number: 2/7 - 3/21 + 2 & 4/14
83.333%
Members or elements
2 & 3/7
2^9 / 2 = 256

36. Describe the relationship between the graphs of x^2 and (1/2)x^2
The second graph is less steep.
4096
67 - 71 - 73
y = 2x^2 - 3

37. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
28. n = 8 - k = 2. n! / k!(n-k)!
A circle centered at -2 - -2 with radius 3.

38. Simplify the expression [(b^2 - c^2) / (b - c)]
y = 2x^2 - 3
1.7
Sqrt 12
(b + c)

39. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
13pi / 2
(n-2) x 180
y = 2x^2 - 3
Arc length = (n/360) x pi(2r) where n is the number of degrees.

40. Write 10 -843 X 10^7 in scientific notation
3 - -3
Area of the base X height = (pi)hr^2
1.0843 X 10^11
1/(x^y)

41. 0^0
An infinite set.
70
Undefined
1

42. What are congruent triangles?
Indeterminable.
.0004809 X 10^11
Triangles with same measure and same side lengths.
x^(4+7) = x^11

43. 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?
2.592 kg
y = (x + 5)/2
Angle/360 x 2(pi)r
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)

44. Formula to calculate arc length?
N! / (n-k)!
... the square of the ratios of the corresponding sides.
Arc length = (n/360) x pi(2r) where n is the number of degrees.
2(pi)r^2 + 2(pi)rh

45. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
3/2 - 5/3
Cd
Move the decimal point to the right x places
Two angles whose sum is 180.

46. What is the formula for compounded interest?
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
(n-2) x 180
(p + q)/5
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.

47. 1/6 in percent?
16.6666%
Two angles whose sum is 90.
288 (8 9 4)
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

48. What is the order of operations?
(base*height) / 2
2sqrt6
The set of input values for a function.
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)

49. 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)
Diameter(Pi)
3
The empty set - denoted by a circle with a diagonal through it.
4.25 - 6 - 22

50. How many sides does a hexagon have?
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
(n-2) x 180
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
6