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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. For similar triangles - the ratio of their corresponding sides is 2:3. What is the ratio of their areas?
Lies opposite the greater angle
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...
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Cd

2. Factor a^2 + 2ab + b^2
Angle/360 x 2(pi)r
(a + b)^2
90pi
$3 -500 in the 9% and $2 -500 in the 7%.

3. What is the area of a regular hexagon with side 6?
0
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
1/2 times 7/3
9 & 6/7

4. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
Sqrt 12
N! / (n-k)!
A reflection about the axis.

5. What are the integers?
All numbers multiples of 1.
Its last two digits are divisible by 4.
Its divisible by 2 and by 3.
N! / (k!)(n-k)!

6. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
II
3 - -3
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
13

7. To multiply a number by 10^x
2 & 3/7
Move the decimal point to the right x places
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
90 degrees

8. What is the side length of an equilateral triangle with altitude 6?
61 - 67
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
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...
Even

9. What is the formula for computing simple interest?
The point of intersection of the systems.
A circle centered on the origin with radius 8.
A = I (1 + rt)
An arc is a portion of a circumference of a circle.

10. To convert a decimal to a percent...
Its divisible by 2 and by 3.
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
A circle centered on the origin with radius 8.
...multiply by 100.

11. Which quadrant is the lower left hand?
87.5%
(a + b)^2
1 & 37/132
III

12. What is a set with no members called?
The set of elements which can be found in either A or B.
The empty set - denoted by a circle with a diagonal through it.
23 - 29
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

13. 70 < all primes< 80
C = 2(pi)r
72
Sector area = (n/360) X (pi)r^2
71 - 73 - 79

14. 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 numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
Undefined
Undefined - because we can'T divide by 0.
9 : 25

15. To convert a percent to a fraction....
Divide by 100.
13
75:11
A subset.

16. Legs 5 - 12. Hypotenuse?
No - the input value has exactly one output.
6
13
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.

17. 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?
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
Ax^2 + bx + c where a -b and c are constants and a /=0
48
Yes. [i.e. f(x) = x^2 - 1

18. If a=-1 and b=3 - what is the value of (4(a^3)(b^2) - 12(a^2)(b^5)) / (16(a^3)(b^2))?
20.5
1 & 37/132
The third side is greater than the difference and less than the sum.
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)

19. A number is divisible by 3 if ...
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
The sum of its digits is divisible by 3.
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
16.6666%

20. 60 < all primes <70
The set of output values for a function.
61 - 67
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
180 degrees

21. Which quandrant is the lower right hand?
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
IV
An isosceles right triangle.
2^9 / 2 = 256

22. Simplify 9^(1/2) X 4^3 X 2^(-6)?
2
Two angles whose sum is 180.
When the function is not defined for all real numbers -; only a subset of the real numbers.
3

23. 8.84 / 5.2
1.7
3
52
F(x) + c

24. Find the surface area of a cylinder with radius 3 and height 12.
1
The third side is greater than the difference and less than the sum.
1/a^6
90pi

25. In a regular polygon with n sides - the formula for the sum of interior angles
Arc length = (n/360) x pi(2r) where n is the number of degrees.
(n-2) x 180
Yes. [i.e. f(x) = x^2 - 1
500

26. a^2 - 2ab + b^2
The greatest value minus the smallest.
(a - b)^2
90 degrees
F(x) - c

27. A company places a 6-symbol code on each product. The code consists of the letter T - followed by 3 numerical digits - and then 2 consonants (Y is a conson). How many codes are possible?
288 (8 9 4)
1
The set of elements found in both A and B.
441000 = 1 10 10 10 21 * 21

28. Pi is a ratio of what to what?
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
Pi is the ratio of a circle'S circumference to its diameter.
Its divisible by 2 and by 3.
The curve opens upward and the vertex is the minimal point on the graph.

29. 2sqrt4 + sqrt4 =
Infinite.
(a - b)(a + b)
3sqrt4
Cd

30. Evaluate 4/11 + 11/12
Two angles whose sum is 180.
Its last two digits are divisible by 4.
1 & 37/132
A circle centered on the origin with radius 8.

31. Legs: 3 - 4. Hypotenuse?
A reflection about the origin.
5
180
Relationship cannot be determined (what if x is negative?)

32. When the 'a' in a parabola is positive....
(amount of decrease/original price) x 100%
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)
Yes - like radicals can be added/subtracted.
The curve opens upward and the vertex is the minimal point on the graph.

33. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
IV
y = (x + 5)/2
2^9 / 2 = 256
28. n = 8 - k = 2. n! / k!(n-k)!

34. Reduce: 4.8 : 0.8 : 1.6
Undefined - because we can'T divide by 0.
10! / (10-3)! = 720
6 : 1 : 2
A grouping of the members within a set based on a shared characteristic.

35. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
11 - 13 - 17 - 19
A circle centered at -2 - -2 with radius 3.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
No - the input value has exactly one output.

36. What is the name for a grouping of the members within a set based on a shared characteristic?
A subset.
83.333%
C = 2(pi)r
Lies opposite the greater angle

37. What are the members or elements of a set?
4a^2(b)
2^9 / 2 = 256
The sum of its digits is divisible by 3.
The objects within a set.

38. A cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
Yes - like radicals can be added/subtracted.
1
31 - 37
1/2 times 7/3

39. What are the irrational numbers?
An arc is a portion of a circumference of a circle.
A 30-60-90 triangle.
20.5
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)

40. 1/8 in percent?
The curve opens upward and the vertex is the minimal point on the graph.
4a^2(b)
12.5%
10! / (10-3)! = 720

41. What does the graph x^2 + y^2 = 64 look like?
A circle centered at -2 - -2 with radius 3.
A circle centered on the origin with radius 8.
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)
y = (x + 5)/2

42. 30< all primes<40
F(x + c)
The greatest value minus the smallest.
4:5
31 - 37

43. A number is divisible by 6 if...
Its divisible by 2 and by 3.
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.
48
Sector area = (n/360) X (pi)r^2

44. Convert 0.7% to a fraction.
2
7 / 1000
.0004809 X 10^11
1.0843 X 10^11

45. What does scientific notation mean?
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
All numbers multiples of 1.
61 - 67
1

46. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
True
A 30-60-90 triangle.
Undefined - because we can'T divide by 0.
(a - b)(a + b)

47. x^(-y)=
F(x) + c
1
2sqrt6
1/(x^y)

48. (-1)^2 =
The steeper the slope.
The empty set - denoted by a circle with a diagonal through it.
F(x) + c
1

49. Formula to find a circle'S circumference from its radius?
1.0843 X 10^11
83.333%
C = 2(pi)r
1/2 times 7/3

50. What is the formula for compounded interest?
62.5%
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.
5
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)

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