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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. Reduce: 4.8 : 0.8 : 1.6
23 - 29
6 : 1 : 2
The two xes after factoring.
1/(x^y)

2. What are the smallest three prime numbers greater than 65?
4725
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.
67 - 71 - 73
(b + c)

3. 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)
4:5
Part = Percent X Whole
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...
4.25 - 6 - 22

4. Surface area for a cylinder?
2(pi)r^2 + 2(pi)rh
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...
Move the decimal point to the right x places
N! / (n-k)!

5. 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?
A circle centered at -2 - -2 with radius 3.
$11 -448
75:11
72

6. What is the ratio of the sides of a 30-60-90 triangle?
1:sqrt3:2
10! / 3!(10-3)! = 120
A chord is a line segment joining two points on a circle.
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

7. Ratio of ages of Anna and Emma is 3:5 and of Emma and Nicolas is 3:5. What is the ratio of Anna to Nicholas' ages?
The second graph is less steep.
9 : 25
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
Members or elements

8. (6sqrt3) x (2sqrt5) =
8
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
The point of intersection of the systems.
288 (8 9 4)

9. What does scientific notation mean?
41 - 43 - 47
Angle/360 x (pi)r^2
18
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

10. Evaluate 3& 2/7 / 1/3
53 - 59
9 & 6/7
83.333%
Sqrt 12

11. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
The overlapping sections.
13pi / 2
The two xes after factoring.
Its negative reciprocal. (-b/a)

12. What is the graph of f(x) shifted upward c units or spaces?
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
Diameter(Pi)
F(x) + c
9 & 6/7

13. If an inequality is multiplied or divided by a negative number....
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
The direction of the inequality is reversed.
(amount of decrease/original price) x 100%
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).

14. What is the set of elements which can be found in either A or B?
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
The union of A and B.
The direction of the inequality is reversed.
72

15. 20<all primes<30
23 - 29
The shortest arc between points A and B on a circle'S diameter.
61 - 67
True

16. What percent of 40 is 22?
Diameter(Pi)
55%
...multiply by 100.
(a - b)(a + b)

17. 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)
The set of elements which can be found in either A or B.
9 & 6/7
An infinite set.

18. Is 0 even or odd?
6
Even
31 - 37
Infinite.

19. Formula for the area of a sector of a circle?
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
Sector area = (n/360) X (pi)r^2
4725
(amount of decrease/original price) x 100%

20. Max and Min lengths for a side of a triangle?
The third side is greater than the difference and less than the sum.
90pi
The two xes after factoring.
The direction of the inequality is reversed.

21. What is an isoceles triangle?
Two equal sides and two equal angles.
9 & 6/7
6
A chord is a line segment joining two points on a circle.

22. Find the surface area of a cylinder with radius 3 and height 12.
(a + b)^2
Cd
y = (x + 5)/2
90pi

23. In a regular polygon with n sides - the formula for the sum of interior angles
(p + q)/5
The sum of its digits is divisible by 3.
x^(4+7) = x^11
(n-2) x 180

24. What is the percent formula?
Part = Percent X Whole
(a - b)(a + b)
(a + b)^2
II

25. Factor x^2 - xy + x.
(a + b)^2
500
6
x(x - y + 1)

26. 60 < all primes <70
288 (8 9 4)
III
x(x - y + 1)
61 - 67

27. Solve the quadratic equation ax^2 + bx + c= 0
A circle centered at -2 - -2 with radius 3.
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
(a + b)^2
A = I (1 + rt)

28. If you have a set of n objects - but you only want to order k of them - what formula do you use to determine the number of permutations?
N! / (n-k)!
41 - 43 - 47
13pi / 2
Its divisible by 2 and by 3.

29. What is a set with no members called?
7 / 1000
The empty set - denoted by a circle with a diagonal through it.
Yes - like radicals can be added/subtracted.
x(x - y + 1)

30. 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)]?
True
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
II
1

31. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
500
4:5
x^(4+7) = x^11
An isosceles right triangle.

32. Evaluate (4^3)^2
27^(-4)
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
4096
N! / (k!)(n-k)!

33. 6w^2 - w - 15 = 0
A grouping of the members within a set based on a shared characteristic.
3/2 - 5/3
Yes. [i.e. f(x) = x^2 - 1
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

34. When the 'a' in a parabola is positive....
A tangent is a line that only touches one point on the circumference of a circle.
The curve opens upward and the vertex is the minimal point on the graph.
The interesection of A and B.
441000 = 1 10 10 10 21 * 21

35. 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?
48
1.7
1
A central angle is an angle formed by 2 radii.

36. What is the 'Range' of a function?
The set of output values for a function.
...multiply by 100.
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
The shortest arc between points A and B on a circle'S diameter.

37. What is the formula for compounded interest?
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.
Indeterminable.
1/a^6
1 & 37/132

38. Legs 6 - 8. Hypotenuse?
Members or elements
0
10
10! / (10-3)! = 720

39. Evaluate 4/11 + 11/12
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
1 & 37/132
The sum of digits is divisible by 9.

40. 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?
y = 2x^2 - 3
71 - 73 - 79
Triangles with same measure and same side lengths.
Undefined

41. For similar triangles - the ratio of their corresponding sides is 2:3. What is the ratio of their areas?
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
y = (x + 5)/2
(p + q)/5
The set of elements which can be found in either A or B.

42. What is the sum of the angles of a triangle?
52
180 degrees
A circle centered at -2 - -2 with radius 3.
The shortest arc between points A and B on a circle'S diameter.

43. How many sides does a hexagon have?
An expression with just one term (-6x - 2a^2)
F(x) - c
6
x= (1.2)(.8)lw

44. How to find the diagonal of a rectangular solid?
8
An angle which is supplementary to an interior angle.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
An isosceles right triangle.

45. What number between 70 & 75 - inclusive - has the greatest number of factors?
180
(p + q)/5
72
(a + b)^2

46. Hector invested $6000. Part was invested in account with 9% simple annual interest - and the rest in account with 7% simple annual interest. If he earned $490 in the first year of these investments - how much did he invest in each account?
$3 -500 in the 9% and $2 -500 in the 7%.
Members or elements
90pi
3

47. Legs 5 - 12. Hypotenuse?
(a - b)(a + b)
13
Two angles whose sum is 180.
The set of elements found in both A and B.

48. The perimeter of a square is 48 inches. The length of its diagonal is:
A central angle is an angle formed by 2 radii.
The sum of digits is divisible by 9.
12sqrt2
Diameter(Pi)

49. (x^2)^4
1
3/2 - 5/3
x^(2(4)) =x^8 = (x^4)^2
N! / (n-k)!

50. Suppose that the graph of f(x) is the result of stretching y=x + 5 away from the x-axis by a factor of 2. What is the new equation for the graph f(x)?
IV
y = (x + 5)/2
90
The sum of digits is divisible by 9.