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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. When does a function automatically have a restricted domain (2)?
10! / (10-3)! = 720
Sector area = (n/360) X (pi)r^2
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
Sqrt 12

2. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
All numbers multiples of 1.
28. n = 8 - k = 2. n! / k!(n-k)!
The greatest value minus the smallest.
No - only like radicals can be added.

3. 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?
10! / 3!(10-3)! = 120
$11 -448
500
An infinite set.

4. x^4 + x^7 =
9 & 6/7
x^(4+7) = x^11
A reflection about the origin.
(base*height) / 2

5. How to find the area of a sector?
Angle/360 x (pi)r^2
A set with no members - denoted by a circle with a diagonal through it.
75:11
A grouping of the members within a set based on a shared characteristic.

6. (a^-1)/a^5
18
A circle centered on the origin with radius 8.
The union of A and B.
1/a^6

7. 1/8 in percent?
4096
When the function is not defined for all real numbers -; only a subset of the real numbers.
75:11
12.5%

8. What is the ratio of the sides of an isosceles right triangle?
1:1:sqrt2
$3 -500 in the 9% and $2 -500 in the 7%.
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
6 : 1 : 2

9. What is the 'union' of A and B?
The set of elements which can be found in either A or B.
9 : 25
13
13pi / 2

10. What is the 'Solution' for a system of linear equations?
The point of intersection of the systems.
A chord is a line segment joining two points on a circle.
A grouping of the members within a set based on a shared characteristic.
Angle/360 x (pi)r^2

11. 70 < all primes< 80
A circle centered on the origin with radius 8.
An isosceles right triangle.
Divide by 100.
71 - 73 - 79

12. What is a set with no members called?
288 (8 9 4)
G(x) = {x}
The empty set - denoted by a circle with a diagonal through it.
True

13. What is the set of elements which can be found in either A or B?
The union of A and B.
2.592 kg
Its divisible by 2 and by 3.
(a + b)^2

14. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
(a - b)(a + b)
(p + q)/5
4725
An isosceles right triangle.

15. The ratio of the areas of two similar polygons is ...
8
... the square of the ratios of the corresponding sides.
No - the input value has exactly one output.
The sum of digits is divisible by 9.

16. Define a 'Term' -
Indeterminable.
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)
III
No - the input value has exactly one output.

17. What is the empty set?
A grouping of the members within a set based on a shared characteristic.
3 - -3
Two equal sides and two equal angles.
A set with no members - denoted by a circle with a diagonal through it.

18. What is a piecewise equation?
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
An isosceles right triangle.
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.
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.

19. What are 'Supplementary angles?'
An isosceles right triangle.
A chord is a line segment joining two points on a circle.
Two angles whose sum is 180.
An infinite set.

20. How many digits are there between the decimal point and the first even digit in the decimal equivalent of 1/[(2^8)(5^3)]
10! / (10-3)! = 720
0
y = 2x^2 - 3
Infinite.

21. What is a parabola?
Ax^2 + bx + c where a -b and c are constants and a /=0
1
(a - b)(a + b)
F(x-c)

22. Reduce: 4.8 : 0.8 : 1.6
180 degrees
An angle which is supplementary to an interior angle.
6 : 1 : 2
The direction of the inequality is reversed.

23. Evaluate (4^3)^2
Members or elements
6
4096
The sum of digits is divisible by 9.

24. Factor a^2 + 2ab + b^2
9 : 25
52
x^(6-3) = x^3
(a + b)^2

25. (-1)^3 =
1
A set with no members - denoted by a circle with a diagonal through it.
90
Undefined - because we can'T divide by 0.

26. What is the name for a grouping of the members within a set based on a shared characteristic?
The union of A and 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.
A subset.
413.03 / 10^4 (move the decimal point 4 places to the left)

27. 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
72
18
.0004809 X 10^11
4a^2(b)

28. Evaluate and write as a mixed number: 2/7 - 3/21 + 2 & 4/14
2 & 3/7
1
5
8

29. A number is divisible by 9 if...
The sum of digits is divisible by 9.
From northeast - counterclockwise. I - II - III - IV
1
(a + b)^2

30. Area of a triangle?
No - the input value has exactly one output.
1:sqrt3:2
(base*height) / 2
2.592 kg

31. 20<all primes<30
55%
3sqrt4
The curve opens upward and the vertex is the minimal point on the graph.
23 - 29

32. Simplify (a^2 + b)^2 - (a^2 - b)^2
The objects within a set.
4a^2(b)
1
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)

33. If an inequality is multiplied or divided by a negative number....
The direction of the inequality is reversed.
Sector area = (n/360) X (pi)r^2
The curve opens upward and the vertex is the minimal point on the graph.
...multiply by 100.

34. 2sqrt4 + sqrt4 =
3sqrt4
The curve opens upward and the vertex is the minimal point on the graph.
4725
(n-2) x 180

35. What is the intersection of A and B?
62.5%
(a - b)(a + b)
The set of elements found in both A and B.
10

36. What is the 'Range' of a series of numbers?
The greatest value minus the smallest.
1
(b + c)
Members or elements

37. What are complementary angles?
F(x + c)
Yes. [i.e. f(x) = x^2 - 1
72
Two angles whose sum is 90.

38. What is a subset?
1
Undefined - because we can'T divide by 0.
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
A grouping of the members within a set based on a shared characteristic.

39. What is the formula for compounded interest?
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.
(amount of decrease/original price) x 100%
Arc length = (n/360) x pi(2r) where n is the number of degrees.
(a - b)(a + b)

40. 30< all primes<40
12.5%
11 - 13 - 17 - 19
31 - 37
A circle centered at -2 - -2 with radius 3.

41. x^6 / x^3
4a^2(b)
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
53 - 59
x^(6-3) = x^3

42. (6sqrt3) x (2sqrt5) =
1
Sector area = (n/360) X (pi)r^2
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
Move the decimal point to the right x places

43. If 10800 is invested at a simple interest rate of 4% - what is the value of the investment after 18 months?
1/a^6
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
$11 -448
16.6666%

44. If the two sides of a triangle are unequal then the longer side...
Lies opposite the greater angle
55%
A = I (1 + rt)
413.03 / 10^4 (move the decimal point 4 places to the left)

45. 7/8 in percent?
87.5%
C = (pi)d
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 sum of its digits is divisible by 3.

46. Which quadrant is the upper right hand?
90
I
The curve opens downward and the vertex is the maximum point on the graph.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

47. 5/8 in percent?
No - only like radicals can be added.
62.5%
The two xes after factoring.
A = I (1 + rt)

48. What is the slope of a horizontal line?
A = I (1 + rt)
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)
0
x= (1.2)(.8)lw

49. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
4:5
An isosceles right triangle.
A reflection about the origin.
A = I (1 + rt)

50. How to find the diagonal of a rectangular solid?
Sector area = (n/360) X (pi)r^2
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
The union of A and B.
A tangent is a line that only touches one point on the circumference of a circle.