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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. 7/8 in percent?
Pi is the ratio of a circle'S circumference to its diameter.
An angle which is supplementary to an interior angle.
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
87.5%

2. 70 < all primes< 80
71 - 73 - 79
75:11
1
4.25 - 6 - 22

3. Length of an arc of a circle?
Indeterminable.
The steeper the slope.
Angle/360 x 2(pi)r
Sqrt 12

4. (a^-1)/a^5
The point of intersection of the systems.
Indeterminable.
1/a^6
1:sqrt3:2

5. For similar triangles - the ratio of their corresponding sides is 2:3. What is the ratio of their areas?
The curve opens downward and the vertex is the maximum point on the graph.
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
2(pi)r^2 + 2(pi)rh

6. Can the input value of a function have more than one output value (i.e. x: y - y1)?
No - the input value has exactly one output.
Two angles whose sum is 180.
61 - 67
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

7. If an inequality is multiplied or divided by a negative number....
1
x^(2(4)) =x^8 = (x^4)^2
The direction of the inequality is reversed.
9 : 25

8. Evaluate 3& 2/7 / 1/3
9 & 6/7
(p + q)/5
C = 2(pi)r
1

9. What is the percent formula?
N! / (n-k)!
2(pi)r^2 + 2(pi)rh
37.5%
Part = Percent X Whole

10. The four angles around a point measure y - 2y - 35 and 55 respectively. What is the value of y?
90
288 (8 9 4)
180
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16

11. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
71 - 73 - 79
3
1/a^6
Members or elements

12. What is the slope of a horizontal line?
Angle/360 x (pi)r^2
0
$3 -500 in the 9% and $2 -500 in the 7%.
x^(4+7) = x^11

13. How many 3-digit positive integers are even and do not contain the digit 4?
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)
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
75:11
288 (8 9 4)

14. Solve the quadratic equation ax^2 + bx + c= 0
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
A tangent is a line that only touches one point on the circumference of a circle.
2sqrt6

15. What is the area of a regular hexagon with side 6?
48
4.25 - 6 - 22
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
10! / (10-3)! = 720

16. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
x^(6-3) = x^3
3
Arc length = (n/360) x pi(2r) where n is the number of degrees.
13pi / 2

17. Formula to find a circle'S circumference from its radius?
C = 2(pi)r
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
I
Two angles whose sum is 180.

18. Which is greater? 27^(-4) or 9^(-8)
1/(x^y)
(a - b)(a + b)
The set of elements which can be found in either A or B.
27^(-4)

19. What are complementary angles?
5 OR -5
Two angles whose sum is 90.
The curve opens downward and the vertex is the maximum point on the graph.
y = (x + 5)/2

20. a^2 + 2ab + b^2
5 OR -5
(a + b)^2
... the square of the ratios of the corresponding sides.
4725

21. 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?
The set of elements which can be found in either A or B.
The overlapping sections.
20.5
441000 = 1 10 10 10 21 * 21

22. What are 'Supplementary angles?'
Two angles whose sum is 180.
6
1
Yes - like radicals can be added/subtracted.

23. 0^0
Undefined
13pi / 2
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
An isosceles right triangle.

24. What does scientific notation mean?
The steeper the slope.
Triangles with same measure and same side lengths.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
The second graph is less steep.

25. What is the surface area of a cylinder with radius 5 and height 8?
130pi
1/2 times 7/3
5
2sqrt6

26. The larger the absolute value of the slope...
Sector area = (n/360) X (pi)r^2
Diameter(Pi)
IV
The steeper the slope.

27. Max and Min lengths for a side of a triangle?
The third side is greater than the difference and less than the sum.
A reflection about the origin.
1/(x^y)
1:1:sqrt2

28. A cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
F(x-c)
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)
6
1

29. Area of a triangle?
90pi
4a^2(b)
10! / (10-3)! = 720
(base*height) / 2

30. Simplify 4sqrt21 X 5sqrt2 / 10sqrt7
62.5%
2sqrt6
x^(4+7) = x^11
Arc length = (n/360) x pi(2r) where n is the number of degrees.

31. 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?
(a + b)^2
N! / (n-k)!
F(x) + c
6 : 1 : 2

32. How to determine percent decrease?
Pi is the ratio of a circle'S circumference to its diameter.
Its divisible by 2 and by 3.
(amount of decrease/original price) x 100%
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

33. What number between 70 & 75 - inclusive - has the greatest number of factors?
The third side is greater than the difference and less than the sum.
Even
72
Lies opposite the greater angle

34. If r - t - s & u are distinct - consecutive prime numbers - less than 31 - which of the following could be an average of them (4 - 4.25 - 6 - 9 - 24 - 22 - 24)
4a^2(b)
2(pi)r^2 + 2(pi)rh
83.333%
4.25 - 6 - 22

35. What are congruent triangles?
(a - b)^2
The empty set - denoted by a circle with a diagonal through it.
0
Triangles with same measure and same side lengths.

36. What are the integers?
All numbers multiples of 1.
Undefined
No - the input value has exactly one output.
3

37. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
x^(2(4)) =x^8 = (x^4)^2
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
A circle centered at -2 - -2 with radius 3.
1

38. (6sqrt3) x (2sqrt5) =
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
A reflection about the origin.
Its divisible by 2 and by 3.

39. 10^6 has how many zeroes?
41 - 43 - 47
(a + b)^2
6
10! / (10-3)! = 720

40. 10<all primes<20
12! / 5!7! = 792
The set of elements found in both A and B.
11 - 13 - 17 - 19
...multiply by 100.

41. 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?
9 : 25
Pi is the ratio of a circle'S circumference to its diameter.
The union of A and B.
The steeper the slope.

42. A number is divisible by 3 if ...
The sum of its digits is divisible by 3.
13
10! / (10-3)! = 720
4725

43. A cylinder has a surface area of 22pi. If the cylinder has a height of 10 - what is the radius?
1
Relationship cannot be determined (what if x is negative?)
Arc length = (n/360) x pi(2r) where n is the number of degrees.
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

44. What is the ratio of the sides of a 30-60-90 triangle?
55%
18
1:sqrt3:2
1 & 37/132

45. Order of quadrants:
From northeast - counterclockwise. I - II - III - IV
G(x) = {x}
x^(4+7) = x^11
The point of intersection of the systems.

46. 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?
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
$3 -500 in the 9% and $2 -500 in the 7%.
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
N! / (n-k)!

47. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
(amount of increase/original price) x 100%
Cd
27^(-4)
53 - 59

48. When the 'a' in a parabola is positive....
5 OR -5
The curve opens upward and the vertex is the minimal point on the graph.
N! / (n-k)!
288 (8 9 4)

49. What is an isoceles triangle?
An angle which is supplementary to an interior angle.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
A circle centered on the origin with radius 8.
Two equal sides and two equal angles.

50. Convert 0.7% to a fraction.
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Divide by 100.
A central angle is an angle formed by 2 radii.
7 / 1000