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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. What is the measure of an exterior angle of a regular pentagon?
No - only like radicals can be added.
72
(b + c)
Ax^2 + bx + c where a -b and c are constants and a /=0

2. 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
The shortest arc between points A and B on a circle'S diameter.
18
Even
9 & 6/7

3. What is an exterior angle?
y = 2x^2 - 3
An angle which is supplementary to an interior angle.
$11 -448
1:sqrt3:2

4. 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.
The curve opens upward and the vertex is the minimal point on the graph.
The direction of the inequality is reversed.
Sector area = (n/360) X (pi)r^2
90 degrees

5. In a regular polygon with n sides - the formula for the sum of interior angles
y = 2x^2 - 3
(n-2) x 180
Divide by 100.
(a - b)^2

6. What is the 'Restricted domain of a function'?
When the function is not defined for all real numbers -; only a subset of the real numbers.
The interesection of A and B.
6
III

7. What is the percent formula?
IV
Part = Percent X Whole
The set of elements found in both A and B.
83.333%

8. There are 10 finalists for the school spelling bee. A first - second - and third place trophy will be awarded. In how many ways can the judges award the 3 prizes?
87.5%
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
10! / (10-3)! = 720
3 - -3

9. What is an arc of a circle?
Two angles whose sum is 90.
Undefined
An arc is a portion of a circumference of a circle.
All numbers multiples of 1.

10. Which is greater? 200x^295 or 10x^294?
The longest arc between points A and B on a circle'S diameter.
A chord is a line segment joining two points on a circle.
Relationship cannot be determined (what if x is negative?)
The curve opens downward and the vertex is the maximum point on the graph.

11. If the two sides of a triangle are unequal then the longer side...
2sqrt6
The curve opens upward and the vertex is the minimal point on the graph.
Lies opposite the greater angle
.0004809 X 10^11

12. A cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
1
The steeper the slope.
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
The two xes after factoring.

13. What is the slope of a horizontal line?
Cd
0
From northeast - counterclockwise. I - II - III - IV
F(x) - c

14. 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?
Indeterminable.
52
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
7 / 1000

15. x^6 / x^3
Part = Percent X Whole
83.333%
x^(6-3) = x^3
The greatest value minus the smallest.

16. 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?
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
2sqrt6
72
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).

17. How to find the area of a sector?
72
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
Angle/360 x (pi)r^2
31 - 37

18. 4.809 X 10^7 =
The longest arc between points A and B on a circle'S diameter.
A chord is a line segment joining two points on a circle.
.0004809 X 10^11
90pi

19. Solve the quadratic equation ax^2 + bx + c= 0
Arc length = (n/360) x pi(2r) where n is the number of degrees.
No - the input value has exactly one output.
87.5%
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

20. What is a major arc?

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21. 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?
Pi is the ratio of a circle'S circumference to its diameter.
48
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
13

22. What is a piecewise equation?
N! / (k!)(n-k)!
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
.0004809 X 10^11
A circle centered at -2 - -2 with radius 3.

23. What is the 'Solution' for a set of inequalities.
(b + c)
10
...multiply by 100.
The overlapping sections.

24. For similar triangles - the ratio of their corresponding sides is 2:3. What is the ratio of their areas?
Undefined
3/2 - 5/3
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.

25. 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?
90pi
1
500
61 - 67

26. Can you subtract 3sqrt4 from sqrt4?
48
Yes - like radicals can be added/subtracted.
Its last two digits are divisible by 4.
The curve opens downward and the vertex is the maximum point on the graph.

27. a^2 + 2ab + b^2
180
(base*height) / 2
Undefined - because we can'T divide by 0.
(a + b)^2

28. How many multiples does a given number have?
4:5
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
Infinite.
The empty set - denoted by a circle with a diagonal through it.

29. What is the graph of f(x) shifted left c units or spaces?
y = (x + 5)/2
F(x + c)
x^(4+7) = x^11
18

30. How to determine percent increase?
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
(amount of increase/original price) x 100%
0
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

31. Formula to calculate arc length?
413.03 / 10^4 (move the decimal point 4 places to the left)
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)
N! / (k!)(n-k)!
Arc length = (n/360) x pi(2r) where n is the number of degrees.

32. What is the graph of f(x) shifted right c units or spaces?
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
(a + b)^2
F(x-c)
Triangles with same measure and same side lengths.

33. 50 < all primes< 60
$11 -448
53 - 59
x^(2(4)) =x^8 = (x^4)^2
(a - b)^2

34. (a^-1)/a^5
6
(a - b)(a + b)
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.
1/a^6

35. P and r are factors of 100. What is greater - pr or 100?
500
1.0843 X 10^11
Indeterminable.
Undefined

36. What is a parabola?
72
y = 2x^2 - 3
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Ax^2 + bx + c where a -b and c are constants and a /=0

37. To multiply a number by 10^x
Part = Percent X Whole
61 - 67
Move the decimal point to the right x places
1:1:sqrt2

38. What is the set of elements found in both A and B?
The interesection of A and B.
II
1
52

39. The larger the absolute value of the slope...
Move the decimal point to the right x places
The steeper the slope.
An arc is a portion of a circumference of a circle.
4725

40. 3/8 in percent?
Part = Percent X Whole
From northeast - counterclockwise. I - II - III - IV
55%
37.5%

41. 10<all primes<20
x^(6-3) = x^3
1/2 times 7/3
The shortest arc between points A and B on a circle'S diameter.
11 - 13 - 17 - 19

42. Which is greater? 64^5 or 16^8
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
A central angle is an angle formed by 2 radii.
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
61 - 67

43. What is a tangent?
The direction of the inequality is reversed.
A tangent is a line that only touches one point on the circumference of a circle.
Infinite.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15

44. Reduce: 4.8 : 0.8 : 1.6
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
6 : 1 : 2
The set of elements which can be found in either A or B.
10! / 3!(10-3)! = 120

45. 6w^2 - w - 15 = 0
The set of elements which can be found in either A or B.
6
3/2 - 5/3
A = pi(r^2)

46. Circumference of 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
Diameter(Pi)
Yes. [i.e. f(x) = x^2 - 1
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

47. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
N! / (n-k)!
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
441000 = 1 10 10 10 21 * 21
3

48. Evaluate (4^3)^2
The set of output values for a function.
2sqrt6
Infinite.
4096

49. 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?
10
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)
No - the input value has exactly one output.
N! / (n-k)!

50. What is it called when a point is reflected to the quadrant opposite it (i.e. I to III or II to IV)?
A reflection about the origin.
...multiply by 100.
x= (1.2)(.8)lw
10