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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
0
180 degrees
y = 2x^2 - 3

2. What is the graph of f(x) shifted downward c units or spaces?
23 - 29
4.25 - 6 - 22
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)
F(x) - c

3. A number is divisible by 9 if...
The empty set - denoted by a circle with a diagonal through it.
48
Its divisible by 2 and by 3.
The sum of digits is divisible by 9.

4. Simplify (a^2 + b)^2 - (a^2 - b)^2
A central angle is an angle formed by 2 radii.
4a^2(b)
Move the decimal point to the right x places
413.03 / 10^4 (move the decimal point 4 places to the left)

5. Circumference of a circle?
Lies opposite the greater angle
N! / (n-k)!
130pi
Diameter(Pi)

6. What is the set of elements found in both A and B?
The interesection of A and B.
3sqrt4
x^(4+7) = x^11
A central angle is an angle formed by 2 radii.

7. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
x^(4+7) = x^11
28. n = 8 - k = 2. n! / k!(n-k)!
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
16.6666%

8. Legs 5 - 12. Hypotenuse?
A = pi(r^2)
The sum of its digits is divisible by 3.
13
130pi

9. What is a subset?
Yes - like radicals can be added/subtracted.
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
A grouping of the members within a set based on a shared characteristic.

10. 3/8 in percent?
55%
6 : 1 : 2
37.5%
71 - 73 - 79

11. When the 'a' in the parabola is negative...
1
6
The curve opens downward and the vertex is the maximum point on the graph.
The union of A and B.

12. 10^6 has how many zeroes?
The overlapping sections.
72
6
A central angle is an angle formed by 2 radii.

13. The slope of a line perpendicular to (a/b)?
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
Its negative reciprocal. (-b/a)
2
N! / (n-k)!

14. 8.84 / 5.2
(b + c)
Area of the base X height = (pi)hr^2
1.7
The curve opens downward and the vertex is the maximum point on the graph.

15. Max and Min lengths for a side of a triangle?
The third side is greater than the difference and less than the sum.
52
3 - -3
Move the decimal point to the right x places

16. What are 'Supplementary angles?'
Two angles whose sum is 180.
55%
28. n = 8 - k = 2. n! / k!(n-k)!
2(pi)r^2 + 2(pi)rh

17. What is the sum of the angles of a triangle?
2^9 / 2 = 256
Yes - like radicals can be added/subtracted.
180 degrees
8

18. 6w^2 - w - 15 = 0
The sum of its digits is divisible by 3.
3/2 - 5/3
72
The objects within a set.

19. How to determine percent decrease?
(amount of decrease/original price) x 100%
A = pi(r^2)
1
The empty set - denoted by a circle with a diagonal through it.

20. Order of quadrants:
Two equal sides and two equal angles.
A tangent is a line that only touches one point on the circumference of a circle.
From northeast - counterclockwise. I - II - III - IV
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

21. 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?
The third side is greater than the difference and less than the sum.
(b + c)
75:11
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

22. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
6
0
A reflection about the axis.

23. What is it called when a point is reflected to the quadrant opposite it (i.e. I to III or II to IV)?
0
A reflection about the origin.
87.5%
A 30-60-90 triangle.

24. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
The overlapping sections.
4725
70
A 30-60-90 triangle.

25. 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?
61 - 67
9 : 25
1.0843 X 10^11
Angle/360 x 2(pi)r

26. Nine coins are tossed simultaneously. In how many of the outcomes will the fourth coin tossed show heads?
Two angles whose sum is 90.
2^9 / 2 = 256
The second graph is less steep.
Undefined - because we can'T divide by 0.

27. Convert 0.7% to a fraction.
C = (pi)d
7 / 1000
... the square of the ratios of the corresponding sides.
.0004809 X 10^11

28. x^2 = 9. What is the value of x?
C = (pi)d
3 - -3
II
A reflection about the axis.

29. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
4:5
No - only like radicals can be added.
5 OR -5
20.5

30. How many multiples does a given number have?
Infinite.
1/2 times 7/3
The curve opens upward and the vertex is the minimal point on the graph.
A chord is a line segment joining two points on a circle.

31. a^2 - b^2
(a - b)(a + b)
(amount of decrease/original price) x 100%
37.5%
1

32. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
From northeast - counterclockwise. I - II - III - IV
4725
(n-2) x 180
10! / (10-3)! = 720

33. Evaluate (4^3)^2
A reflection about the origin.
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
4096
16.6666%

34. What does the graph x^2 + y^2 = 64 look like?
A circle centered on the origin with radius 8.
$3 -500 in the 9% and $2 -500 in the 7%.
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
2sqrt6

35. 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?
9 : 25
55%
61 - 67
$3 -500 in the 9% and $2 -500 in the 7%.

36. What is a chord of a circle?
3
x(x - y + 1)
A chord is a line segment joining two points on a circle.
72

37. What are the smallest three prime numbers greater than 65?
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
The point of intersection of the systems.
67 - 71 - 73
x^(4+7) = x^11

38. A number is divisible by 6 if...
441000 = 1 10 10 10 21 * 21
An infinite set.
Its divisible by 2 and by 3.
4:5

39. Legs: 3 - 4. Hypotenuse?
130pi
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)
5
Yes. [i.e. f(x) = x^2 - 1

40. 70 < all primes< 80
Two equal sides and two equal angles.
71 - 73 - 79
An isosceles right triangle.
Area of the base X height = (pi)hr^2

41. Define a 'Term' -
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)
Two angles whose sum is 90.
1
F(x) - c

42. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
13pi / 2
72
Ax^2 + bx + c where a -b and c are constants and a /=0
C = 2(pi)r

43. What is a central angle?
(n-2) x 180
10! / 3!(10-3)! = 120
A central angle is an angle formed by 2 radii.
2sqrt6

44. If an inequality is multiplied or divided by a negative number....
(p + q)/5
1:1:sqrt2
13
The direction of the inequality is reversed.

45. What is the graph of f(x) shifted left c units or spaces?
F(x + c)
The point of intersection of the systems.
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
87.5%

46. What is the third quartile of the following data set: 44 - 58 - 63 - 63 - 68 - 70 - 82
70
The overlapping sections.
No - only like radicals can be added.
9 : 25

47. Area of a triangle?
(base*height) / 2
1:1:sqrt2
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
x^(6-3) = x^3

48. Suppose that the graph of f(x) is the result of stretching y=x + 5 away from the x-axis by a factor of 2. What is the new equation for the graph f(x)?
12.5%
61 - 67
y = (x + 5)/2
180

49. 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?
9 & 6/7
500
441000 = 1 10 10 10 21 * 21
3

50. Factor a^2 + 2ab + b^2
(a + b)^2
2.592 kg
1
The curve opens upward and the vertex is the minimal point on the graph.