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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. Convert 0.7% to a fraction.
7 / 1000
Its last two digits are divisible by 4.
Move the decimal point to the right x places
A set with no members - denoted by a circle with a diagonal through it.

2. 5/6 in percent?
x^(6-3) = x^3
(base*height) / 2
83.333%
The curve opens upward and the vertex is the minimal point on the graph.

3. Evaluate (4^3)^2
4096
IV
72
288 (8 9 4)

4. What is the name for a grouping of the members within a set based on a shared characteristic?
75:11
Yes. [i.e. f(x) = x^2 - 1
3/2 - 5/3
A subset.

5. Which is greater? 64^5 or 16^8
180 degrees
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
4a^2(b)
12.5%

6. Write 10 -843 X 10^7 in scientific notation
Two equal sides and two equal angles.
1.0843 X 10^11
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...
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.

7. When the 'a' in a parabola is positive....
8
500
The curve opens upward and the vertex is the minimal point on the graph.
0

8. Which is greater? 27^(-4) or 9^(-8)
The two xes after factoring.
27^(-4)
2 & 3/7
1

9. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
A circle centered at -2 - -2 with radius 3.
61 - 67
Two angles whose sum is 90.
500

10. What are the smallest three prime numbers greater than 65?
All numbers multiples of 1.
Lies opposite the greater angle
67 - 71 - 73
(a + b)^2

11. A number is divisible by 9 if...
7 / 1000
1/(x^y)
The sum of digits is divisible by 9.
4.25 - 6 - 22

12. 7/8 in percent?
0
71 - 73 - 79
87.5%
y = 2x^2 - 3

13. Which quandrant is the lower right hand?
The steeper the slope.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
12.5%
IV

14. Reduce: 4.8 : 0.8 : 1.6
6 : 1 : 2
4096
2^9 / 2 = 256
288 (8 9 4)

15. (-1)^2 =
An expression with just one term (-6x - 2a^2)
1
The set of elements found in both A and B.
1.7

16. Evaluate 3& 2/7 / 1/3
1
9 & 6/7
A reflection about the axis.
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

17. What is the third quartile of the following data set: 44 - 58 - 63 - 63 - 68 - 70 - 82
70
x^(6-3) = x^3
A chord is a line segment joining two points on a circle.
The longest arc between points A and B on a circle'S diameter.

18. What does the graph x^2 + y^2 = 64 look like?
F(x + c)
Pi is the ratio of a circle'S circumference to its diameter.
A circle centered on the origin with radius 8.
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16

19. 4.809 X 10^7 =
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.
True
.0004809 X 10^11
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15

20. What is the side length of an equilateral triangle with altitude 6?
(n-2) x 180
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...
5 OR -5
70

21. How to determine percent decrease?
(amount of decrease/original price) x 100%
4a^2(b)
A set with no members - denoted by a circle with a diagonal through it.
28. n = 8 - k = 2. n! / k!(n-k)!

22. a^2 + 2ab + b^2
(a + b)^2
3 - -3
3
1

23. 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?
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
F(x) - c
75:11
10! / 3!(10-3)! = 120

24. 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?
9 : 25
4.25 - 6 - 22
441000 = 1 10 10 10 21 * 21
(a + b)^2

25. (12sqrt15) / (2sqrt5) =
The objects within a set.
A = pi(r^2)
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)
(12/2) x (sqrt15 / sqrt5) = 6sqrt3

26. What is the formula for computing simple interest?
x= (1.2)(.8)lw
2
70
A = I (1 + rt)

27. What are complementary angles?
Two angles whose sum is 90.
(b + c)
An angle which is supplementary to an interior angle.
No - only like radicals can be added.

28. 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)]?
180
1:sqrt3:2
True
An angle which is supplementary to an interior angle.

29. How to find the diagonal of a rectangular solid?
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
1:1:sqrt2
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

30. Define a 'monomial'
3
Triangles with same measure and same side lengths.
An expression with just one term (-6x - 2a^2)
8

31. 70 < all primes< 80
71 - 73 - 79
Divide by 100.
9 & 6/7
Pi is the ratio of a circle'S circumference to its diameter.

32. 30< all primes<40
11 - 13 - 17 - 19
31 - 37
The sum of its digits is divisible by 3.
1:1:sqrt2

33. Simplify the expression [(b^2 - c^2) / (b - c)]
413.03 / 10^4 (move the decimal point 4 places to the left)
10! / 3!(10-3)! = 120
(b + c)
441000 = 1 10 10 10 21 * 21

34. Circumference of a circle?
Its divisible by 2 and by 3.
12! / 5!7! = 792
An infinite set.
Diameter(Pi)

35. What is the graph of f(x) shifted downward c units or spaces?
180 degrees
Ax^2 + bx + c where a -b and c are constants and a /=0
F(x) - c
F(x + c)

36. 5x^2 - 35x -55 = 0
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
When the function is not defined for all real numbers -; only a subset of the real numbers.
An isosceles right triangle.

37. Legs 5 - 12. Hypotenuse?
N! / (n-k)!
13
441000 = 1 10 10 10 21 * 21
Pi is the ratio of a circle'S circumference to its diameter.

38. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
3
(amount of decrease/original price) x 100%
Diameter(Pi)
The overlapping sections.

39. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
4:5
3 - -3
1
90 degrees

40. 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?
The curve opens upward and the vertex is the minimal point on the graph.
N! / (k!)(n-k)!
3
(a + b)^2

41. How many digits are there between the decimal point and the first even digit in the decimal equivalent of 1/[(2^8)(5^3)]
1:1:sqrt2
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
0
Its divisible by 2 and by 3.

42. What is the name of set with a number of elements which cannot be counted?
x^(2(4)) =x^8 = (x^4)^2
90 degrees
Divide by 100.
An infinite set.

43. Simplify (a^2 + b)^2 - (a^2 - b)^2
Cd
75:11
(a - b)(a + b)
4a^2(b)

44. How many sides does a hexagon have?
A circle centered at -2 - -2 with radius 3.
x^(4+7) = x^11
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
6

45. What is the 'Range' of a series of numbers?
180
The greatest value minus the smallest.
A chord is a line segment joining two points on a circle.
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)

46. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
Move the decimal point to the right x places
An isosceles right triangle.
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
62.5%

47. Which quadrant is the upper right hand?
Angle/360 x (pi)r^2
I
Sector area = (n/360) X (pi)r^2
180

48. Formula to find a circle'S circumference from its radius?
83.333%
C = 2(pi)r
48
Yes - like radicals can be added/subtracted.

49. For what values should the domain be restricted for the function f(x) = sqrt(x + 8)
The third side is greater than the difference and less than the sum.
8
A grouping of the members within a set based on a shared characteristic.
12sqrt2

50. What is the formula for compounded interest?
(a - b)^2
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)
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