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GRE Math: Common Errors

Subjects : gre, math

Instructions:

Answer 50 questions in 15 minutes.
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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 a chord of a circle?
2
No - only like radicals can be added.
A chord is a line segment joining two points on a circle.
Diameter(Pi)

2. The larger the absolute value of the slope...
The set of input values for a function.
Area of the base X height = (pi)hr^2
The steeper the slope.
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)

3. If Madagascar'S exports totaled 1.3 billion in 2009 - and 4% came from China - what was the value in millions of the country'S exports to China?
N! / (n-k)!
52
2sqrt6
x^(6-3) = x^3

4. What is an isoceles triangle?
Two equal sides and two equal angles.
Two angles whose sum is 90.
41 - 43 - 47
C = (pi)d

5. If the two sides of a triangle are unequal then the longer side...
Lies opposite the greater angle
The shortest arc between points A and B on a circle'S diameter.
13pi / 2
F(x) + c

6. 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?
413.03 / 10^4 (move the decimal point 4 places to the left)
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 infinite set.
The direction of the inequality is reversed.

7. (-1)^3 =
(amount of decrease/original price) x 100%
II
Ax^2 + bx + c where a -b and c are constants and a /=0
1

8. 40 < all primes<50
The overlapping sections.
(a - b)(a + b)
1
41 - 43 - 47

9. What are 'Supplementary angles?'
Pi is the ratio of a circle'S circumference to its diameter.
The set of output values for a function.
Two angles whose sum is 180.
When the function is not defined for all real numbers -; only a subset of the real numbers.

10. 10^6 has how many zeroes?
1/2 times 7/3
(b + c)
3
6

11. How to find the circumference of a circle which circumscribes a square?
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
Even
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
An isosceles right triangle.

12. Which quandrant is the lower right hand?
IV
2 & 3/7
16.6666%
72

13. Define a 'Term' -
23 - 29
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)
The set of input values for a function.
12.5%

14. 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
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
From northeast - counterclockwise. I - II - III - IV
18
1

15. What is the intersection of A and B?
A subset.
The set of elements found in both A and B.
The empty set - denoted by a circle with a diagonal through it.
A set with no members - denoted by a circle with a diagonal through it.

16. Legs 5 - 12. Hypotenuse?
13
Divide by 100.
No - the input value has exactly one output.
A grouping of the members within a set based on a shared characteristic.

17. x^2 = 9. What is the value of x?
The curve opens upward and the vertex is the minimal point on the graph.
G(x) = {x}
3 - -3
1.7

18. How to determine percent decrease?
(a + b)^2
Undefined
(amount of decrease/original price) x 100%
The longest arc between points A and B on a circle'S diameter.

19. 7/8 in percent?
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
87.5%
Sector area = (n/360) X (pi)r^2
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.

20. Simplify 4sqrt21 X 5sqrt2 / 10sqrt7
11 - 13 - 17 - 19
The two xes after factoring.
10
2sqrt6

21. What is the graph of f(x) shifted right c units or spaces?
F(x-c)
1:1:sqrt2
4725
4a^2(b)

22. 8.84 / 5.2
5 OR -5
The curve opens downward and the vertex is the maximum point on the graph.
90 degrees
1.7

23. Simplify 9^(1/2) X 4^3 X 2^(-6)?
$11 -448
Two angles whose sum is 180.
(a - b)^2
3

24. What is the measure of an exterior angle of a regular pentagon?
F(x) + c
A = pi(r^2)
(n-2) x 180
72

25. Define an 'expression'.
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)
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)
1/2 times 7/3
$11 -448

26. (a^-1)/a^5
Ax^2 + bx + c where a -b and c are constants and a /=0
Part = Percent X Whole
(amount of decrease/original price) x 100%
1/a^6

27. Evaluate 3& 2/7 / 1/3
9 & 6/7
The overlapping sections.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
8

28. Legs: 3 - 4. Hypotenuse?
5
2
Sqrt 12
C = (pi)d

29. 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?
...multiply by 100.
10! / 3!(10-3)! = 120
75:11
Infinite.

30. Formula of rectangle where l increases by 20% and w decreases by 20%
x= (1.2)(.8)lw
61 - 67
A chord is a line segment joining two points on a circle.
90pi

31. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
The longest arc between points A and B on a circle'S diameter.
4:5
1
IV

32. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
Its negative reciprocal. (-b/a)
An isosceles right triangle.
An infinite set.
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]

33. What is the absolute value function?
G(x) = {x}
$11 -448
Its negative reciprocal. (-b/a)
3/2 - 5/3

34. (6sqrt3) x (2sqrt5) =
(b + c)
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
No - the input value has exactly one output.
Indeterminable.

35. How many 3-digit positive integers are even and do not contain the digit 4?
288 (8 9 4)
Members or elements
Part = Percent X Whole
Its last two digits are divisible by 4.

36. 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?
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
N! / (k!)(n-k)!
Pi is the ratio of a circle'S circumference to its diameter.
3

37. Max and Min lengths for a side of a triangle?
Undefined
11 - 13 - 17 - 19
C = 2(pi)r
The third side is greater than the difference and less than the sum.

38. 50 < all primes< 60
Move the decimal point to the right x places
53 - 59
1:1:sqrt2
288 (8 9 4)

39. What is the coefficient of the x^2 term in the product of (x + 1)(x + 2)(x -1)?
(a + b)^2
Yes - like radicals can be added/subtracted.
2
G(x) = {x}

40. When does a function automatically have a restricted domain (2)?
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
N! / (n-k)!
x= (1.2)(.8)lw
The shortest arc between points A and B on a circle'S diameter.

41. Whats the difference between factors and multiples?
The overlapping sections.
Undefined
Factors are few - multiples are many.
1

42. What is a major arc?
$11 -448
3 - -3
2sqrt6
The longest arc between points A and B on a circle'S diameter.

43. Formula to find a circle'S circumference from its diameter?
C = (pi)d
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)
8
(a + b)^2

44. The slope of a line perpendicular to (a/b)?
The union of A and B.
Its negative reciprocal. (-b/a)
True
67 - 71 - 73

45. 70 < all primes< 80
I
71 - 73 - 79
2sqrt6
6 : 1 : 2

46. Which quadrant is the upper left hand?
(b + c)
(a + b)^2
Arc length = (n/360) x pi(2r) where n is the number of degrees.
II

47. 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?
The interesection of A and B.
72
IV
500

48. 2sqrt4 + sqrt4 =
1
x^(6-3) = x^3
3sqrt4
(a - b)(a + b)

49. 25^(1/2) or sqrt. 25 =
2sqrt6
1
5 OR -5
Its last two digits are divisible by 4.

50. Which is greater? 27^(-4) or 9^(-8)
27^(-4)
Yes. [i.e. f(x) = x^2 - 1
31 - 37
3 - -3

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