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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 cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
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)
1
90 degrees
Angle/360 x (pi)r^2

2. 413.03 x 10^(-4) =
The sum of digits is divisible by 9.
413.03 / 10^4 (move the decimal point 4 places to the left)
Its divisible by 2 and by 3.
A central angle is an angle formed by 2 radii.

3. Can the output value of a function have more than one input value?
IV
Yes. [i.e. f(x) = x^2 - 1
A reflection about the axis.
6 : 1 : 2

4. (12sqrt15) / (2sqrt5) =
70
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
3
The overlapping sections.

5. sqrt 2(sqrt 6)=
Angle/360 x (pi)r^2
.0004809 X 10^11
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
Sqrt 12

6. The larger the absolute value of the slope...
A = pi(r^2)
The steeper the slope.
1
(p + q)/5

7. Which is greater? 27^(-4) or 9^(-8)
1/2 times 7/3
27^(-4)
x^(6-3) = x^3
x^(2(4)) =x^8 = (x^4)^2

8. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
An isosceles right triangle.
(b + c)
Two angles whose sum is 90.
1

9. What is a central angle?
70
(p + q)/5
A central angle is an angle formed by 2 radii.
Lies opposite the greater angle

10. Formula of rectangle where l increases by 20% and w decreases by 20%
I
1 & 37/132
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
x= (1.2)(.8)lw

11. x^2 = 9. What is the value of x?
3 - -3
1/(x^y)
28. n = 8 - k = 2. n! / k!(n-k)!
1.0843 X 10^11

12. What is the 'Range' of a series of numbers?
6
The greatest value minus the smallest.
From northeast - counterclockwise. I - II - III - IV
Its negative reciprocal. (-b/a)

13. Nine coins are tossed simultaneously. In how many of the outcomes will the fourth coin tossed show heads?
6
2^9 / 2 = 256
Angle/360 x (pi)r^2
3sqrt4

14. The ratio of the areas of two similar polygons is ...
130pi
1
... the square of the ratios of the corresponding sides.
No - the input value has exactly one output.

15. Describe the relationship between the graphs of x^2 and (1/2)x^2
2sqrt6
The second graph is less steep.
x^(6-3) = x^3
The objects within a set.

16. What is the sum of the angles of a triangle?
288 (8 9 4)
180 degrees
4.25 - 6 - 22
Yes - like radicals can be added/subtracted.

17. 70 < all primes< 80
71 - 73 - 79
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
52
72

18. A number is divisible by 9 if...
75:11
Its negative reciprocal. (-b/a)
The sum of digits is divisible by 9.
2 & 3/7

19. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
Lies opposite the greater angle
12! / 5!7! = 792
61 - 67
4.25 - 6 - 22

20. x^(-y)=
II
1/(x^y)
N! / (n-k)!
27^(-4)

21. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
1
3 - -3
28. n = 8 - k = 2. n! / k!(n-k)!
A reflection about the origin.

22. x^4 + x^7 =
A = pi(r^2)
Its divisible by 2 and by 3.
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)
x^(4+7) = x^11

23. A number is divisible by 3 if ...
71 - 73 - 79
(n-2) x 180
The sum of its digits is divisible by 3.
52

24. 1/2 divided by 3/7 is the same as
1/2 times 7/3
An arc is a portion of a circumference of a circle.
An isosceles right triangle.
41 - 43 - 47

25. What does the graph x^2 + y^2 = 64 look like?
A circle centered on the origin with radius 8.
12sqrt2
(a - b)^2
13pi / 2

26. What is a parabola?
Ax^2 + bx + c where a -b and c are constants and a /=0
1
(a - b)(a + b)
1/a^6

27. Formula to find a circle'S circumference from its radius?
C = 2(pi)r
Its last two digits are divisible by 4.
90pi
6

28. Can you simplify sqrt72?
The longest arc between points A and B on a circle'S diameter.
y = (x + 5)/2
1
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.

29. How to determine percent decrease?
The objects within a set.
(amount of decrease/original price) x 100%
52
72

30. What is an isoceles triangle?
Two equal sides and two equal angles.
(p + q)/5
1/(x^y)
28. n = 8 - k = 2. n! / k!(n-k)!

31. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
An isosceles right triangle.
x^(6-3) = x^3
Cd
Triangles with same measure and same side lengths.

32. How many digits are there between the decimal point and the first even digit in the decimal equivalent of 1/[(2^8)(5^3)]
6 : 1 : 2
90pi
0
C = 2(pi)r

33. What is the graph of f(x) shifted right c units or spaces?
... the square of the ratios of the corresponding sides.
Divide by 100.
F(x-c)
F(x) + c

34. What is the set of elements found in both A and B?
90pi
53 - 59
Diameter(Pi)
The interesection of A and B.

35. 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?
2.592 kg
Triangles with same measure and same side lengths.
4a^2(b)
The interesection of A and B.

36. Suppose that the graph of f(x) is the result of sliding the graph of y=2x^2 down 3 units of spaces. What is the new equation?
y = 2x^2 - 3
1
2 & 3/7
The empty set - denoted by a circle with a diagonal through it.

37. What is a tangent?
Undefined - because we can'T divide by 0.
180 degrees
(amount of decrease/original price) x 100%
A tangent is a line that only touches one point on the circumference of a circle.

38. What is the ratio of the sides of an isosceles right triangle?
1:1:sqrt2
An angle which is supplementary to an interior angle.
2
The sum of its digits is divisible by 3.

39. When the 'a' in a parabola is positive....
The set of elements found in both A and B.
500
Two angles whose sum is 180.
The curve opens upward and the vertex is the minimal point on the graph.

40. 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?
The overlapping sections.
x^(6-3) = x^3
N! / (n-k)!
Two equal sides and two equal angles.

41. What percent of 40 is 22?
55%
(a + b)^2
Even
Its negative reciprocal. (-b/a)

42. 10<all primes<20
11 - 13 - 17 - 19
52
IV
23 - 29

43. What is the intersection of A and B?
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
The steeper the slope.
The direction of the inequality is reversed.
The set of elements found in both A and B.

44. (-1)^2 =
37.5%
N! / (n-k)!
1
The curve opens upward and the vertex is the minimal point on the graph.

45. 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 set of output values for a function.
A chord is a line segment joining two points on a circle.
11 - 13 - 17 - 19
$3 -500 in the 9% and $2 -500 in the 7%.

46. Which is greater? 64^5 or 16^8
1:sqrt3:2
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
Its divisible by 2 and by 3.
C = 2(pi)r

47. A number is divisible by 4 is...
Its last two digits are divisible by 4.
...multiply by 100.
37.5%
53 - 59

48. What is a set with no members called?
11 - 13 - 17 - 19
The second graph is less steep.
413.03 / 10^4 (move the decimal point 4 places to the left)
The empty set - denoted by a circle with a diagonal through it.

49. Find the surface area of a cylinder with radius 3 and height 12.
x(x - y + 1)
90pi
A subset.
When the function is not defined for all real numbers -; only a subset of the real numbers.

50. Formula for the area of a circle?
A = pi(r^2)
55%
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
Cd