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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. The ratio of the areas of two similar polygons is ...
Move the decimal point to the right x places
3 - -3
... the square of the ratios of the corresponding sides.
1

2. 20<all primes<30
Its negative reciprocal. (-b/a)
Move the decimal point to the right x places
Two angles whose sum is 90.
23 - 29

3. Formula of rectangle where l increases by 20% and w decreases by 20%
x= (1.2)(.8)lw
Part = Percent X Whole
Pi is the ratio of a circle'S circumference to its diameter.
1

4. Simplify the expression (p^2 - q^2)/ -5(q - p)
The curve opens downward and the vertex is the maximum point on the graph.
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
(p + q)/5
An angle which is supplementary to an interior angle.

5. 50 < all primes< 60
An isosceles right triangle.
53 - 59
288 (8 9 4)
A = pi(r^2)

6. 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 overlapping sections.
90 degrees
3
Diameter(Pi)

7. Which quadrant is the upper left hand?
(b + c)
II
The longest arc between points A and B on a circle'S diameter.
(n-2) x 180

8. Formula to find a circle'S circumference from its diameter?
C = (pi)d
4.25 - 6 - 22
2^9 / 2 = 256
Sqrt 12

9. What is the name of set with a number of elements which cannot be counted?
An infinite set.
Cd
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
27^(-4)

10. Can you add sqrt 3 and sqrt 5?
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
Undefined
No - only like radicals can be added.
11 - 13 - 17 - 19

11. 413.03 x 10^(-4) =
(amount of decrease/original price) x 100%
413.03 / 10^4 (move the decimal point 4 places to the left)
72
12! / 5!7! = 792

12. 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?
4725
N! / (n-k)!
The third side is greater than the difference and less than the sum.
The interesection of A and B.

13. (x^2)^4
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
Two equal sides and two equal angles.
10
x^(2(4)) =x^8 = (x^4)^2

14. Define a 'monomial'
(a + b)^2
An expression with just one term (-6x - 2a^2)
3 - -3
(a - b)(a + b)

15. 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?
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
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...
9 : 25

16. 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?
90 degrees
The overlapping sections.
A chord is a line segment joining two points on a circle.
y = 2x^2 - 3

17. The slope of a line perpendicular to (a/b)?
A 30-60-90 triangle.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
x(x - y + 1)
Its negative reciprocal. (-b/a)

18. What are the irrational numbers?

19. What is a tangent?
IV
61 - 67
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
A tangent is a line that only touches one point on the circumference of a circle.

20. A brick with dimensions 10. 15 and 25 weighs 1.5 kg. A second brick (same density) has dimensions 12 - 18 - and 30. What is the weight of the second brick?
Triangles with same measure and same side lengths.
67 - 71 - 73
2.592 kg
Members or elements

21. Evaluate (4^3)^2
4096
$11 -448
The empty set - denoted by a circle with a diagonal through it.
The sum of digits is divisible by 9.

22. What is the percent formula?
12sqrt2
Part = Percent X Whole
A = I (1 + rt)
0

23. (-1)^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)
1
441000 = 1 10 10 10 21 * 21
(a - b)(a + b)

24. Simplify 9^(1/2) X 4^3 X 2^(-6)?
Sector area = (n/360) X (pi)r^2
IV
52
3

25. What is an arc of a circle?
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 reflection about the axis.
An arc is a portion of a circumference of a circle.
A set with a number of elements which can be counted.

26. x^4 + x^7 =
x^(4+7) = x^11
1.0843 X 10^11
Factors are few - multiples are many.
90pi

27. What is the area of a regular hexagon with side 6?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
The two xes after factoring.
Two angles whose sum is 180.
.0004809 X 10^11

28. 1/8 in percent?
130pi
x^(2(4)) =x^8 = (x^4)^2
12.5%
Angle/360 x (pi)r^2

29. 4.809 X 10^7 =
.0004809 X 10^11
The curve opens downward and the vertex is the maximum point on the graph.
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.
The set of input values for a function.

30. 10^6 has how many zeroes?
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
The sum of digits is divisible by 9.
6
6 : 1 : 2

31. 40 < all primes<50
Arc length = (n/360) x pi(2r) where n is the number of degrees.
41 - 43 - 47
The curve opens downward and the vertex is the maximum point on the graph.
441000 = 1 10 10 10 21 * 21

32. Which quadrant is the upper right hand?
2^9 / 2 = 256
Its negative reciprocal. (-b/a)
(a - b)(a + b)
I

33. 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
18
(a - b)(a + b)
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
1

34. What is the maximum value for the function g(x) = (-2x^2) -1?
1
2
When the function is not defined for all real numbers -; only a subset of the real numbers.
...multiply by 100.

35. 70 < all primes< 80
71 - 73 - 79
41 - 43 - 47
Relationship cannot be determined (what if x is negative?)
1/a^6

36. 5/8 in percent?
180 degrees
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
$11 -448
62.5%

37. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
13pi / 2
The empty set - denoted by a circle with a diagonal through it.
The sum of its digits is divisible by 3.
(a + b)^2

38. Legs 5 - 12. Hypotenuse?
13
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
1 & 37/132
1

39. How to find the area of a sector?
83.333%
Angle/360 x (pi)r^2
Its divisible by 2 and by 3.
An expression with just one term (-6x - 2a^2)

40. What are the real numbers?
$3 -500 in the 9% and $2 -500 in the 7%.
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)
Ax^2 + bx + c where a -b and c are constants and a /=0
83.333%

41. Reduce: 4.8 : 0.8 : 1.6
2^9 / 2 = 256
Arc length = (n/360) x pi(2r) where n is the number of degrees.
6 : 1 : 2
The overlapping sections.

42. How many sides does a hexagon have?
4725
A = I (1 + rt)
A grouping of the members within a set based on a shared characteristic.
6

43. What is the ratio of the sides of an isosceles right triangle?
12! / 5!7! = 792
75:11
1:1:sqrt2
C = (pi)d

44. Factor a^2 + 2ab + b^2
A = I (1 + rt)
90
(a + b)^2
The direction of the inequality is reversed.

45. 0^0
A reflection about the axis.
Infinite.
2(pi)r^2 + 2(pi)rh
Undefined

46. 30< all primes<40
31 - 37
7 / 1000
5 OR -5
$11 -448

47. 5/6 in percent?
1
Undefined
83.333%
(b + c)

48. 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).
1:sqrt3:2
The interesection of A and B.
A set with no members - denoted by a circle with a diagonal through it.

49. Formula for the area of a circle?
C = (pi)d
III
A = pi(r^2)
The sum of digits is divisible by 9.

50. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
23 - 29
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
3
9 : 25