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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 objects in a set are called two names:
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)
The sum of digits is divisible by 9.
90 degrees
Members or elements

2. Length of an arc of a circle?
7 / 1000
Angle/360 x 2(pi)r
6 : 1 : 2
288 (8 9 4)

3. 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)]?
Its divisible by 2 and by 3.
The two xes after factoring.
True
Even

4. 2sqrt4 + sqrt4 =
3sqrt4
(p + q)/5
A reflection about the origin.
The sum of its digits is divisible by 3.

5. What is the 'Range' of a series of numbers?
The greatest value minus the smallest.
90 degrees
16.6666%
1

6. 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
16.6666%
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...
18
Two equal sides and two equal angles.

7. What is the graph of f(x) shifted right c units or spaces?
90pi
F(x-c)
1/a^6
Its divisible by 2 and by 3.

8. How many 3-digit positive integers are even and do not contain the digit 4?
288 (8 9 4)
The curve opens upward and the vertex is the minimal point on the graph.
180 degrees
31 - 37

9. What is the surface area of a cylinder with radius 5 and height 8?
2 & 3/7
The empty set - denoted by a circle with a diagonal through it.
61 - 67
130pi

10. a^2 + 2ab + b^2
Indeterminable.
A tangent is a line that only touches one point on the circumference of a circle.
(a + b)^2
37.5%

11. What is the third quartile of the following data set: 44 - 58 - 63 - 63 - 68 - 70 - 82
x^(2(4)) =x^8 = (x^4)^2
70
3 - -3
Angle/360 x 2(pi)r

12. 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?
2^9 / 2 = 256
The set of elements which can be found in either A or B.
A = I (1 + rt)
10! / 3!(10-3)! = 120

13. What is the 'Solution' for a system of linear equations?
37.5%
The point of intersection of the systems.
1
An isosceles right triangle.

14. Whats the difference between factors and multiples?
Factors are few - multiples are many.
Divide by 100.
72
A central angle is an angle formed by 2 radii.

15. How many multiples does a given number have?
1/(x^y)
(a - b)(a + b)
The direction of the inequality is reversed.
Infinite.

16. Evaluate and write as a mixed number: 2/7 - 3/21 + 2 & 4/14
2 & 3/7
Members or elements
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)
52

17. To multiply a number by 10^x
Move the decimal point to the right x places
Divide by 100.
x^(4+7) = x^11
2^9 / 2 = 256

18. 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?
1/(x^y)
Part = Percent X Whole
500
A subset.

19. 5/8 in percent?
C = 2(pi)r
53 - 59
62.5%
...multiply by 100.

20. 60 < all primes <70
I
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
61 - 67
7 / 1000

21. 50 < all primes< 60
1
53 - 59
The sum of digits is divisible by 9.
1

22. What is the maximum value for the function g(x) = (-2x^2) -1?
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)
Its negative reciprocal. (-b/a)
1
Undefined

23. 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?
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
52
18
5 OR -5

24. What is the 'Restricted domain of a function'?
An infinite set.
When the function is not defined for all real numbers -; only a subset of the real numbers.
The union of A and B.
7 / 1000

25. How to find the circumference of a circle which circumscribes a square?
13pi / 2
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
12sqrt2
F(x + c)

26. What is the ratio of the sides of a 30-60-90 triangle?
Infinite.
1/(x^y)
Sector area = (n/360) X (pi)r^2
1:sqrt3:2

27. What percent of 40 is 22?
500
The direction of the inequality is reversed.
1:sqrt3:2
55%

28. What are the roots of the quadrinomial x^2 + 2x + 1?
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
The sum of digits is divisible by 9.
The two xes after factoring.
62.5%

29. What is the ratio of the surface area of a cube with an edge of 10 to the surface area of a rectangular solid with dimensions 2 - 4 - and 6?
75:11
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
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)
The steeper the slope.

30. Hector invested $6000. Part was invested in account with 9% simple annual interest - and the rest in account with 7% simple annual interest. If he earned $490 in the first year of these investments - how much did he invest in each account?
6
$3 -500 in the 9% and $2 -500 in the 7%.
Indeterminable.
(b + c)

31. The perimeter of a square is 48 inches. The length of its diagonal is:
N! / (k!)(n-k)!
8
12sqrt2
Two angles whose sum is 90.

32. When the 'a' in the parabola is negative...
The curve opens downward and the vertex is the maximum point on the graph.
$11 -448
1
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

33. Evaluate 3& 2/7 / 1/3
(a + b)^2
9 & 6/7
1
No - the input value has exactly one output.

34. P and r are factors of 100. What is greater - pr or 100?
1.7
Indeterminable.
An expression with just one term (-6x - 2a^2)
1/2 times 7/3

35. In a triangle where the two legs are 4 and 3 - what is the value of a line directly intersecting the middle coming from the meeting point of the two legs?
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
90pi
Sector area = (n/360) X (pi)r^2
Undefined

36. 70 < all primes< 80
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
Area of the base X height = (pi)hr^2
71 - 73 - 79
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.

37. sqrt 2(sqrt 6)=
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
Sqrt 12
1.0843 X 10^11
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

38. Solve the quadratic equation ax^2 + bx + c= 0
(base*height) / 2
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
180 degrees
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

39. Write 10 -843 X 10^7 in scientific notation
(amount of increase/original price) x 100%
72
1:sqrt3:2
1.0843 X 10^11

40. What is the slope of a horizontal line?
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
71 - 73 - 79
20.5
0

41. What is an exterior angle?
1:1:sqrt2
An angle which is supplementary to an interior angle.
The shortest arc between points A and B on a circle'S diameter.
2(pi)r^2 + 2(pi)rh

42. Evaluate 4/11 + 11/12
1
1 & 37/132
2 & 3/7
1

43. Can you add sqrt 3 and sqrt 5?
Sector area = (n/360) X (pi)r^2
No - only like radicals can be added.
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
3 - -3

44. 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?
10! / (10-3)! = 720
An infinite set.
67 - 71 - 73
(a - b)^2

45. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
0
The sum of its digits is divisible by 3.
The direction of the inequality is reversed.
3

46. 6w^2 - w - 15 = 0
3sqrt4
y = (x + 5)/2
3/2 - 5/3
1

47. What is the slope of a vertical line?

48. 3/8 in percent?
37.5%
1/2 times 7/3
Triangles with same measure and same side lengths.
72

49. Describe the relationship between the graphs of x^2 and (1/2)x^2
The point of intersection of the systems.
The second graph is less steep.
2
A grouping of the members within a set based on a shared characteristic.

50. Formula of rectangle where l increases by 20% and w decreases by 20%
x= (1.2)(.8)lw
441000 = 1 10 10 10 21 * 21
An expression with just one term (-6x - 2a^2)
Two angles whose sum is 180.