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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. 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
41 - 43 - 47
75:11
Relationship cannot be determined (what if x is negative?)

2. Can you add sqrt 3 and sqrt 5?
The third side is greater than the difference and less than the sum.
Ax^2 + bx + c where a -b and c are constants and a /=0
No - only like radicals can be added.
1 & 37/132

3. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
The second graph is less steep.
13pi / 2
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
A = I (1 + rt)

4. Can the input value of a function have more than one output value (i.e. x: y - y1)?
0
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
18
No - the input value has exactly one output.

5. If 10800 is invested at a simple interest rate of 4% - what is the value of the investment after 18 months?
$11 -448
The steeper the slope.
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)
5

6. 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))?
67 - 71 - 73
20.5
1
The third side is greater than the difference and less than the sum.

7. What is the 'domain' of a function?
27^(-4)
The set of input values for a function.
0
1

8. (a^-1)/a^5
Its negative reciprocal. (-b/a)
Factors are few - multiples are many.
Two angles whose sum is 90.
1/a^6

9. A number is divisible by 3 if ...
N! / (k!)(n-k)!
The second graph is less steep.
The sum of its digits is divisible by 3.
C = (pi)d

10. What is the formula for compounded interest?
$11 -448
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.
Sector area = (n/360) X (pi)r^2
A circle centered on the origin with radius 8.

11. What is an exterior angle?
180
An angle which is supplementary to an interior angle.
1.7
(a + b)^2

12. 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?
A reflection about the axis.
10! / (10-3)! = 720
An infinite set.
Its last two digits are divisible by 4.

13. When the 'a' in the parabola is negative...
Move the decimal point to the right x places
The curve opens downward and the vertex is the maximum point on the graph.
3/2 - 5/3
1/a^6

14. Legs 5 - 12. Hypotenuse?
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
75:11
Its negative reciprocal. (-b/a)
13

15. Is 0 even or odd?
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.
Even
83.333%
500

16. What is it called when a point is reflected to the quadrant opposite it (i.e. I to III or II to IV)?
61 - 67
1
A reflection about the origin.
All numbers multiples of 1.

17. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
An arc is a portion of a circumference of a circle.
A 30-60-90 triangle.
A grouping of the members within a set based on a shared characteristic.
Move the decimal point to the right x places

18. What are the smallest three prime numbers greater than 65?
3/2 - 5/3
67 - 71 - 73
(amount of decrease/original price) x 100%
An angle which is supplementary to an interior angle.

19. What is the maximum value for the function g(x) = (-2x^2) -1?
1
The set of input values for a function.
A reflection about the axis.
1/2 times 7/3

20. The ratio of the areas of two similar polygons is ...
1.7
... the square of the ratios of the corresponding sides.
1
The sum of digits is divisible by 9.

21. If an inequality is multiplied or divided by a negative number....
5
The direction of the inequality is reversed.
C = 2(pi)r
Two angles whose sum is 180.

22. Legs 6 - 8. Hypotenuse?
90
Factors are few - multiples are many.
10
Undefined - because we can'T divide by 0.

23. A number is divisible by 9 if...
4a^2(b)
75:11
A reflection about the axis.
The sum of digits is divisible by 9.

24. What is the absolute value function?
The longest arc between points A and B on a circle'S diameter.
70
G(x) = {x}
Sector area = (n/360) X (pi)r^2

25. Simplify the expression [(b^2 - c^2) / (b - c)]
Ax^2 + bx + c where a -b and c are constants and a /=0
(b + c)
Diameter(Pi)
Yes. [i.e. f(x) = x^2 - 1

26. How to find the area of a sector?
Sector area = (n/360) X (pi)r^2
Angle/360 x (pi)r^2
Diameter(Pi)
An isosceles right triangle.

27. Evaluate and write as a mixed number: 2/7 - 3/21 + 2 & 4/14
x^(2(4)) =x^8 = (x^4)^2
2 & 3/7
1/2 times 7/3
A = pi(r^2)

28. T or F? Given d -e &f =/ 0 - [(d^3)e(f^5)] / 2d(e^3) / [3(d^2)(e^3)(f^7)] / [6(e^5)(f^2)]?
A subset.
441000 = 1 10 10 10 21 * 21
True
An infinite set.

29. 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?
1
10! / 3!(10-3)! = 120
The set of elements which can be found in either A or B.
Triangles with same measure and same side lengths.

30. Can you simplify sqrt72?
A = pi(r^2)
x(x - y + 1)
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)

31. What is the graph of f(x) shifted right c units or spaces?
(b + c)
F(x-c)
1/a^6
75:11

32. Legs: 3 - 4. Hypotenuse?
The steeper the slope.
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
87.5%

33. 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?
6
(b + c)
2.592 kg
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)

34. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
2^9 / 2 = 256
61 - 67
4:5
Undefined

35. Solve the quadratic equation ax^2 + bx + c= 0
All numbers multiples of 1.
Area of the base X height = (pi)hr^2
C = 2(pi)r
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

36. What is the empty set?
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
9 : 25
4.25 - 6 - 22
A set with no members - denoted by a circle with a diagonal through it.

37. What is a subset?
A grouping of the members within a set based on a shared characteristic.
Triangles with same measure and same side lengths.
C = (pi)d
A circle centered at -2 - -2 with radius 3.

38. What is a chord of a circle?
1.0843 X 10^11
The second graph is less steep.
A chord is a line segment joining two points on a circle.
1:sqrt3:2

39. The objects in a set are called two names:
52
Members or elements
All numbers multiples of 1.
An isosceles right triangle.

40. If the two sides of a triangle are unequal then the longer side...
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
9 & 6/7
20.5
Lies opposite the greater angle

41. Simplify 9^(1/2) X 4^3 X 2^(-6)?
A set with a number of elements which can be counted.
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.
Lies opposite the greater angle

42. 413.03 x 10^(-4) =
The point of intersection of the systems.
413.03 / 10^4 (move the decimal point 4 places to the left)
No - only like radicals can be added.
The union of A and B.

43. Describe the relationship between the graphs of x^2 and (1/2)x^2
27^(-4)
1
The second graph is less steep.
2^9 / 2 = 256

44. What is a tangent?
When the function is not defined for all real numbers -; only a subset of the real numbers.
$3 -500 in the 9% and $2 -500 in the 7%.
90 degrees
A tangent is a line that only touches one point on the circumference of a circle.

45. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
Its divisible by 2 and by 3.
67 - 71 - 73
Cd
The set of input values for a function.

46. Reduce: 4.8 : 0.8 : 1.6
61 - 67
6 : 1 : 2
37.5%
Area of the base X height = (pi)hr^2

47. What are complementary angles?
6 : 1 : 2
Move the decimal point to the right x places
1
Two angles whose sum is 90.

48. For what values should the domain be restricted for the function f(x) = sqrt(x + 8)
87.5%
Area of the base X height = (pi)hr^2
8
An isosceles right triangle.

49. When the 'a' in a parabola is positive....
12! / 5!7! = 792
1
The curve opens upward and the vertex is the minimal point on the graph.
13

50. Nine coins are tossed simultaneously. In how many of the outcomes will the fourth coin tossed show heads?
2^9 / 2 = 256
180 degrees
G(x) = {x}
1:1:sqrt2