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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. 8.84 / 5.2
1.7
75:11
The point of intersection of the systems.
Infinite.

2. 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
A = pi(r^2)
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)
(b + c)
18

3. A cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
1:sqrt3:2
1
A subset.
6

4. Simplify (a^2 + b)^2 - (a^2 - b)^2
4a^2(b)
Cd
True
70

5. What are the smallest three prime numbers greater than 65?
The curve opens downward and the vertex is the maximum point on the graph.
67 - 71 - 73
3sqrt4
Angle/360 x 2(pi)r

6. Which is greater? 27^(-4) or 9^(-8)
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
27^(-4)
The sum of digits is divisible by 9.
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...

7. 7/8 in percent?
The shortest arc between points A and B on a circle'S diameter.
1
Undefined - because we can'T divide by 0.
87.5%

8. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
4:5
(a + b)^2
A central angle is an angle formed by 2 radii.
A circle centered on the origin with radius 8.

9. 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 point of intersection of the systems.
72
Lies opposite the greater angle
441000 = 1 10 10 10 21 * 21

10. Formula to find a circle'S circumference from its diameter?
Yes - like radicals can be added/subtracted.
A set with no members - denoted by a circle with a diagonal through it.
48
C = (pi)d

11. What is the absolute value function?
G(x) = {x}
8
3/2 - 5/3
27^(-4)

12. (a^-1)/a^5
4725
1/a^6
Two angles whose sum is 180.
(a - b)^2

13. 5/8 in percent?
12.5%
62.5%
F(x) - c
48

14. What is the maximum value for the function g(x) = (-2x^2) -1?
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
6 : 1 : 2
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.
1

15. When does a function automatically have a restricted domain (2)?
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
0
4.25 - 6 - 22
Infinite.

16. Formula to find a circle'S circumference from its radius?
180 degrees
2 & 3/7
A reflection about the axis.
C = 2(pi)r

17. What is the slope of a horizontal line?
0
A tangent is a line that only touches one point on the circumference of a circle.
$3 -500 in the 9% and $2 -500 in the 7%.
The sum of its digits is divisible by 3.

18. The perimeter of a square is 48 inches. The length of its diagonal is:
Factors are few - multiples are many.
12sqrt2
3/2 - 5/3
The direction of the inequality is reversed.

19. Suppose you have a set of n objects - and you want to select k of them - but the order doesn'T matter. What formula do you use to determine the number of combinations of n objects taken k at a time?
N! / (k!)(n-k)!
1:sqrt3:2
52
(a + b)^2

20. What does scientific notation mean?
A set with a number of elements which can be counted.
... the square of the ratios of the corresponding sides.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
Angle/360 x 2(pi)r

21. A number is divisible by 9 if...
x^(4+7) = x^11
The sum of its digits is divisible by 3.
The sum of digits is divisible by 9.
70

22. 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?
Indeterminable.
N! / (n-k)!
0
1/2 times 7/3

23. How many 3-digit positive integers are even and do not contain the digit 4?
Undefined
288 (8 9 4)
(n-2) x 180
An arc is a portion of a circumference of a circle.

24. What is an isoceles triangle?
1
Two equal sides and two equal angles.
16.6666%
Even

25. a^2 - b^2 =
(a - b)(a + b)
1.0843 X 10^11
11 - 13 - 17 - 19
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)

26. Simplify the expression [(b^2 - c^2) / (b - c)]
1 & 37/132
1
1:1:sqrt2
(b + c)

27. Evaluate and write as a mixed number: 2/7 - 3/21 + 2 & 4/14
2 & 3/7
23 - 29
The shortest arc between points A and B on a circle'S diameter.
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.

28. (6sqrt3) x (2sqrt5) =
Even
18
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
180 degrees

29. What is the set of elements found in both A and B?
(a - b)(a + b)
5 OR -5
41 - 43 - 47
The interesection of A and B.

30. 40 < all primes<50
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
.0004809 X 10^11
41 - 43 - 47
(amount of decrease/original price) x 100%

31. What is the area of a regular hexagon with side 6?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
1.7
y = (x + 5)/2
0

32. What is an arc of a circle?
An arc is a portion of a circumference of a circle.
7 / 1000
An infinite set.
(amount of decrease/original price) x 100%

33. a^0 =
8
18
1
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.

34. For what values should the domain be restricted for the function f(x) = sqrt(x + 8)
8
31 - 37
An infinite set.
x(x - y + 1)

35. What are the rational numbers?
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
53 - 59
(a - b)(a + b)

36. 20<all primes<30
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
72
23 - 29
A tangent is a line that only touches one point on the circumference of a circle.

37. Which is greater? 64^5 or 16^8
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
4096
1
413.03 / 10^4 (move the decimal point 4 places to the left)

38. What is the intersection of A and B?
Indeterminable.
3sqrt4
41 - 43 - 47
The set of elements found in both A and B.

39. Can you simplify sqrt72?
6
Its negative reciprocal. (-b/a)
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
180

40. Formula of rectangle where l increases by 20% and w decreases by 20%
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...
13
x= (1.2)(.8)lw
20.5

41. Legs 5 - 12. Hypotenuse?
13
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
F(x) + c
90

42. What is a finite set?
A set with a number of elements which can be counted.
4:5
1/2 times 7/3
6

43. To convert a percent to a fraction....
Divide by 100.
3 - -3
x^(6-3) = x^3
2^9 / 2 = 256

44. What is the 'Solution' for a system of linear equations?
The point of intersection of the systems.
(a + b)^2
75:11
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.

45. Which quadrant is the upper right hand?
3 - -3
True
I
6

46. What is the order of operations?
Two equal sides and two equal angles.
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
The overlapping sections.
61 - 67

47. What is the formula for compounded interest?
Area of the base X height = (pi)hr^2
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.
Diameter(Pi)
True

48. Describe the relationship between the graphs of x^2 and (1/2)x^2
61 - 67
90 degrees
75:11
The second graph is less steep.

49. 413.03 x 10^(-4) =
4:5
2
413.03 / 10^4 (move the decimal point 4 places to the left)
Its last two digits are divisible by 4.

50. 1/6 in percent?
28. n = 8 - k = 2. n! / k!(n-k)!
3 - -3
71 - 73 - 79
16.6666%