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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. How to determine percent increase?
(amount of increase/original price) x 100%
(b + c)
Move the decimal point to the right x places
18

2. The four angles around a point measure y - 2y - 35 and 55 respectively. What is the value of y?
67 - 71 - 73
90
(a + b)^2
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)

3. What is the 'Range' of a series of numbers?
The greatest value minus the smallest.
16.6666%
61 - 67
The objects within a set.

4. Formula to find a circle'S circumference from its radius?
No - the input value has exactly one output.
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
III
C = 2(pi)r

5. 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
8
28. n = 8 - k = 2. n! / k!(n-k)!
x^(4+7) = x^11

6. 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?
1
A subset.
y = 2x^2 - 3
x^(2(4)) =x^8 = (x^4)^2

7. What is the measure of an exterior angle of a regular pentagon?
2
1 & 37/132
72
Infinite.

8. What is the graph of f(x) shifted upward c units or spaces?
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
2
4.25 - 6 - 22
F(x) + c

9. (-1)^3 =
1
No - only like radicals can be added.
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)
Cd

10. Describe the relationship between the graphs of x^2 and (1/2)x^2
Angle/360 x (pi)r^2
7 / 1000
The second graph is less steep.
Yes. [i.e. f(x) = x^2 - 1

11. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
11 - 13 - 17 - 19
$3 -500 in the 9% and $2 -500 in the 7%.
Cd
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

12. 3/8 in percent?
37.5%
90
III
No - only like radicals can be added.

13. If 10800 is invested at a simple interest rate of 4% - what is the value of the investment after 18 months?
F(x) - c
The direction of the inequality is reversed.
28. n = 8 - k = 2. n! / k!(n-k)!
$11 -448

14. What is an exterior angle?
Triangles with same measure and same side lengths.
72
4.25 - 6 - 22
An angle which is supplementary to an interior angle.

15. What number between 70 & 75 - inclusive - has the greatest number of factors?
N! / (k!)(n-k)!
A = I (1 + rt)
72
An angle which is supplementary to an interior angle.

16. 5/6 in percent?
2
83.333%
All numbers multiples of 1.
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)

17. What does the graph x^2 + y^2 = 64 look like?
A circle centered on the origin with radius 8.
1/a^6
61 - 67
2(pi)r^2 + 2(pi)rh

18. 60 < all primes <70
61 - 67
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
Angle/360 x 2(pi)r
83.333%

19. Can the output value of a function have more than one input value?
Yes. [i.e. f(x) = x^2 - 1
4096
$11 -448
75:11

20. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
Members or elements
12sqrt2
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

21. A number is divisible by 6 if...
(a - b)(a + b)
Undefined
1
Its divisible by 2 and by 3.

22. How to find the circumference of a circle which circumscribes a square?
Yes. [i.e. f(x) = x^2 - 1
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
C = (pi)d
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).

23. The number of degrees in the largest angle of a triangle inscribed in a circle - in which the diameter of the circle is one side of the triangle.
75:11
The curve opens upward and the vertex is the minimal point on the graph.
90 degrees
87.5%

24. What is the area of a regular hexagon with side 6?
62.5%
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
413.03 / 10^4 (move the decimal point 4 places to the left)
(amount of decrease/original price) x 100%

25. Which quadrant is the lower left hand?
The curve opens downward and the vertex is the maximum point on the graph.
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
The sum of digits is divisible by 9.
III

26. 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?
500
Factors are few - multiples are many.
3
8

27. Simplify 4sqrt21 X 5sqrt2 / 10sqrt7
2sqrt6
The interesection of A and B.
12.5%
I

28. 7/8 in percent?
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
The two xes after factoring.
2
87.5%

29. How to find the area of a sector?
441000 = 1 10 10 10 21 * 21
Ax^2 + bx + c where a -b and c are constants and a /=0
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)
Angle/360 x (pi)r^2

30. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
An isosceles right triangle.
(a - b)(a + b)
x^(4+7) = x^11
1

31. Simplify the expression (p^2 - q^2)/ -5(q - p)
(p + q)/5
Infinite.
True
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.

32. a^2 - b^2 =
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
Its divisible by 2 and by 3.
6
(a - b)(a + b)

33. 10^6 has how many zeroes?
Diameter(Pi)
6
The two xes after factoring.
Yes. [i.e. f(x) = x^2 - 1

34. When the 'a' in a parabola is positive....
The curve opens upward and the vertex is the minimal point on the graph.
A reflection about the axis.
(b + c)
1

35. Length of an arc of a circle?
(a + b)^2
Angle/360 x 2(pi)r
N! / (k!)(n-k)!
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15

36. Which quandrant is the lower right hand?
413.03 / 10^4 (move the decimal point 4 places to the left)
$3 -500 in the 9% and $2 -500 in the 7%.
IV
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.

37. Legs 5 - 12. Hypotenuse?
1
13
(a + b)^2
A set with no members - denoted by a circle with a diagonal through it.

38. 5x^2 - 35x -55 = 0
The overlapping sections.
1/2 times 7/3
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
Infinite.

39. Which quadrant is the upper right hand?
I
When the function is not defined for all real numbers -; only a subset of the real numbers.
A set with a number of elements which can be counted.
13pi / 2

40. Volume for a cylinder?
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
Sector area = (n/360) X (pi)r^2
Area of the base X height = (pi)hr^2
Angle/360 x 2(pi)r

41. 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)?
31 - 37
y = (x + 5)/2
288 (8 9 4)
0

42. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
An expression with just one term (-6x - 2a^2)
A circle centered at -2 - -2 with radius 3.
III
A circle centered on the origin with radius 8.

43. What is the third quartile of the following data set: 44 - 58 - 63 - 63 - 68 - 70 - 82
The sum of its digits is divisible by 3.
70
C = (pi)d
3/2 - 5/3

44. 40 < all primes<50
An angle which is supplementary to an interior angle.
41 - 43 - 47
Undefined
A subset.

45. Which is greater? 200x^295 or 10x^294?
2 & 3/7
The sum of digits is divisible by 9.
Relationship cannot be determined (what if x is negative?)
A 30-60-90 triangle.

46. Is 0 even or odd?
4096
3sqrt4
Even
IV

47. How many 3-digit positive integers are even and do not contain the digit 4?
The set of elements which can be found in either A or B.
1
288 (8 9 4)
2^9 / 2 = 256

48. Write 10 -843 X 10^7 in scientific notation
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
5 OR -5
1.0843 X 10^11
Divide by 100.

49. 5/8 in percent?
62.5%
5 OR -5
28. n = 8 - k = 2. n! / k!(n-k)!
The set of input values for a function.

50. Evaluate (4^3)^2
1.7
4096
The set of elements found in both A and B.
An angle which is supplementary to an interior angle.