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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. 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?
1/a^6
55%
441000 = 1 10 10 10 21 * 21
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

2. 1/8 in percent?
1:1:sqrt2
90 degrees
12.5%
F(x-c)

3. Legs: 3 - 4. Hypotenuse?
5
(a + b)^2
1/2 times 7/3
(a - b)(a + b)

4. 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
The overlapping sections.
A = I (1 + rt)
4096

5. What is the graph of f(x) shifted left c units or spaces?
The greatest value minus the smallest.
37.5%
F(x + c)
Ax^2 + bx + c where a -b and c are constants and a /=0

6. What are the smallest three prime numbers greater than 65?
67 - 71 - 73
6
13pi / 2
37.5%

7. 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?
Arc length = (n/360) x pi(2r) where n is the number of degrees.
(a - b)(a + b)
52
The direction of the inequality is reversed.

8. 20<all primes<30
23 - 29
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
A tangent is a line that only touches one point on the circumference of a circle.
A reflection about the origin.

9. 5/6 in percent?
83.333%
Two equal sides and two equal angles.
x= (1.2)(.8)lw
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)

10. Can you subtract 3sqrt4 from sqrt4?
Ax^2 + bx + c where a -b and c are constants and a /=0
Yes - like radicals can be added/subtracted.
11 - 13 - 17 - 19
1

11. What is a chord of a circle?
90 degrees
x^(2(4)) =x^8 = (x^4)^2
A chord is a line segment joining two points on a circle.
Triangles with same measure and same side lengths.

12. Simplify the expression [(b^2 - c^2) / (b - c)]
(b + c)
The objects within a set.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
2.592 kg

13. 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?
500
N! / (n-k)!
The sum of its digits is divisible by 3.
4096

14. What is the sum of the angles of a triangle?
180 degrees
A set with no members - denoted by a circle with a diagonal through it.
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...
(a - b)(a + b)

15. Which is greater? 64^5 or 16^8
F(x) - c
x^(2(4)) =x^8 = (x^4)^2
3
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16

16. Which quadrant is the upper right hand?
I
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
1/a^6
1 & 37/132

17. What is the name of set with a number of elements which cannot be counted?
2 & 3/7
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)
5 OR -5
An infinite set.

18. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
Its last two digits are divisible by 4.
y = (x + 5)/2
180 degrees
4:5

19. Write 10 -843 X 10^7 in scientific notation
The two xes after factoring.
1.0843 X 10^11
The curve opens upward and the vertex is the minimal point on the graph.
Undefined

20. A cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
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
13
(amount of decrease/original price) x 100%

21. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
Its negative reciprocal. (-b/a)
The set of elements found in both A and B.
An angle which is supplementary to an interior angle.
A reflection about the axis.

22. What is the area of a regular hexagon with side 6?
Members or elements
Angle/360 x 2(pi)r
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
Area of the base X height = (pi)hr^2

23. The ratio of the areas of two similar polygons is ...
No - only like radicals can be added.
... the square of the ratios of the corresponding sides.
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)
87.5%

24. 3/8 in percent?
4096
75:11
37.5%
Lies opposite the greater angle

25. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
Cd
10
A central angle is an angle formed by 2 radii.
F(x + c)

26. In a regular polygon with n sides - the formula for the sum of interior angles
An angle which is supplementary to an interior angle.
1.7
(n-2) x 180
4096

27. Area of a triangle?
2^9 / 2 = 256
The curve opens downward and the vertex is the maximum point on the graph.
2sqrt6
(base*height) / 2

28. For similar triangles - the ratio of their corresponding sides is 2:3. What is the ratio of their areas?
180
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
12sqrt2
Ax^2 + bx + c where a -b and c are constants and a /=0

29. Length of an arc of a circle?
The sum of its digits is divisible by 3.
Angle/360 x (pi)r^2
Angle/360 x 2(pi)r
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

30. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
The curve opens upward and the vertex is the minimal point on the graph.
A 30-60-90 triangle.
41 - 43 - 47

31. What is the measure of an exterior angle of a regular pentagon?
72
5
Yes. [i.e. f(x) = x^2 - 1
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

32. Volume for a cylinder?
Yes. [i.e. f(x) = x^2 - 1
...multiply by 100.
Area of the base X height = (pi)hr^2
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)

33. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
0
The point of intersection of the systems.
3
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.

34. x^6 / x^3
x^(6-3) = x^3
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
1:1:sqrt2
A grouping of the members within a set based on a shared characteristic.

35. What is the ratio of the sides of a 30-60-90 triangle?
Relationship cannot be determined (what if x is negative?)
A reflection about the axis.
1:sqrt3:2
4:5

36. Factor a^2 + 2ab + b^2
Two angles whose sum is 90.
1
3sqrt4
(a + b)^2

37. The larger the absolute value of the slope...
The curve opens downward and the vertex is the maximum point on the graph.
2sqrt6
The steeper the slope.
2.592 kg

38. If 10800 is invested at a simple interest rate of 4% - what is the value of the investment after 18 months?
180
5 OR -5
20.5
$11 -448

39. Which is greater? 200x^295 or 10x^294?
The greatest value minus the smallest.
Relationship cannot be determined (what if x is negative?)
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
A central angle is an angle formed by 2 radii.

40. (x^2)^4
G(x) = {x}
A tangent is a line that only touches one point on the circumference of a circle.
x^(2(4)) =x^8 = (x^4)^2
Undefined - because we can'T divide by 0.

41. What is the ratio of the sides of an isosceles right triangle?
1:1:sqrt2
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
y = 2x^2 - 3
$3 -500 in the 9% and $2 -500 in the 7%.

42. What is the third quartile of the following data set: 44 - 58 - 63 - 63 - 68 - 70 - 82
70
3
2.592 kg
Lies opposite the greater angle

43. What is an exterior angle?
An expression with just one term (-6x - 2a^2)
An angle which is supplementary to an interior angle.
II
6 : 1 : 2

44. A number is divisible by 4 is...
Its last two digits are divisible by 4.
A set with a number of elements which can be counted.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
7 / 1000

45. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
x^(2(4)) =x^8 = (x^4)^2
13pi / 2
Its last two digits are divisible by 4.
N! / (k!)(n-k)!

46. What is the side length of an equilateral triangle with altitude 6?
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...
The longest arc between points A and B on a circle'S diameter.
(a - b)(a + b)
13

47. What is a tangent?
A tangent is a line that only touches one point on the circumference of a circle.
Area of the base X height = (pi)hr^2
A reflection about the origin.
(a - b)^2

48. a^2 - 2ab + b^2
Angle/360 x (pi)r^2
12! / 5!7! = 792
(a - b)^2
2sqrt6

49. A number is divisible by 3 if ...
The set of elements which can be found in either A or B.
The sum of its digits is divisible by 3.
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
I

50. How to determine percent increase?
(amount of increase/original price) x 100%
Two angles whose sum is 90.
3/2 - 5/3
11 - 13 - 17 - 19