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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. How to determine percent decrease?
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
(amount of decrease/original price) x 100%
9 : 25
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

2. 20<all primes<30
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
4:5
23 - 29
Sqrt 12

3. a^2 - b^2
(a - b)(a + b)
Ax^2 + bx + c where a -b and c are constants and a /=0
413.03 / 10^4 (move the decimal point 4 places to the left)
2(pi)r^2 + 2(pi)rh

4. What is the slope of a horizontal line?
No - only like radicals can be added.
0
2.592 kg
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)

5. What is the name for a grouping of the members within a set based on a shared characteristic?
Angle/360 x (pi)r^2
10! / 3!(10-3)! = 120
12.5%
A subset.

6. a^2 - b^2 =
The curve opens downward and the vertex is the maximum point on the graph.
37.5%
(a - b)(a + b)
4.25 - 6 - 22

7. Formula of rectangle where l increases by 20% and w decreases by 20%
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
288 (8 9 4)
0
x= (1.2)(.8)lw

8. 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.
67 - 71 - 73
$3 -500 in the 9% and $2 -500 in the 7%.
(amount of increase/original price) x 100%

9. What is the order of operations?
$11 -448
y = 2x^2 - 3
A reflection about the origin.
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)

10. What is it called when a point is reflected to the quadrant opposite it (i.e. I to III or II to IV)?
A reflection about the origin.
13pi / 2
No - the input value has exactly one output.
A 30-60-90 triangle.

11. What is the surface area of a cylinder with radius 5 and height 8?
(n-2) x 180
x^(2(4)) =x^8 = (x^4)^2
130pi
The sum of digits is divisible by 9.

12. What is the 'Range' of a function?
Part = Percent X Whole
The set of output values for a function.
10! / 3!(10-3)! = 120
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

13. If 10800 is invested at a simple interest rate of 4% - what is the value of the investment after 18 months?
Lies opposite the greater angle
1
2sqrt6
$11 -448

14. Nine coins are tossed simultaneously. In how many of the outcomes will the fourth coin tossed show heads?
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.
2^9 / 2 = 256
$3 -500 in the 9% and $2 -500 in the 7%.
C = (pi)d

15. (x^2)^4
x^(6-3) = x^3
90 degrees
Cd
x^(2(4)) =x^8 = (x^4)^2

16. 1/8 in percent?
4a^2(b)
1.0843 X 10^11
2 & 3/7
12.5%

17. 5/6 in percent?
83.333%
When the function is not defined for all real numbers -; only a subset of the real numbers.
No - only like radicals can be added.
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]

18. Can you simplify sqrt72?
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
72
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.
75:11

19. How many multiples does a given number have?
x^(4+7) = x^11
90pi
10! / (10-3)! = 720
Infinite.

20. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
(a - b)(a + b)
A 30-60-90 triangle.
0
A central angle is an angle formed by 2 radii.

21. Legs 5 - 12. Hypotenuse?
5 OR -5
13
1/2 times 7/3
x^(6-3) = x^3

22. What number between 70 & 75 - inclusive - has the greatest number of factors?
72
1
27^(-4)
N! / (k!)(n-k)!

23. Formula for the area of a sector of a circle?
Sector area = (n/360) X (pi)r^2
9 : 25
The sum of its digits is divisible by 3.
4.25 - 6 - 22

24. 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?
72
(b + c)
10! / 3!(10-3)! = 120
III

25. What are the real numbers?
12! / 5!7! = 792
(p + q)/5
31 - 37
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)

26. To convert a percent to a fraction....
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
1
Divide by 100.
4:5

27. Solve the quadratic equation ax^2 + bx + c= 0
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
Lies opposite the greater angle
A grouping of the members within a set based on a shared characteristic.
500

28. What is the empty set?
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
A set with no members - denoted by a circle with a diagonal through it.
The two xes after factoring.
The set of elements which can be found in either A or B.

29. Factor x^2 - xy + x.
x(x - y + 1)
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
130pi
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

30. 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?
52
(base*height) / 2
The interesection of A and B.
500

31. x^6 / x^3
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
The shortest arc between points A and B on a circle'S diameter.
Yes - like radicals can be added/subtracted.
x^(6-3) = x^3

32. What is the absolute value function?
G(x) = {x}
13pi / 2
3
90 degrees

33. 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?
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
10! / 3!(10-3)! = 120
2.592 kg
The interesection of A and B.

34. Is 0 even or odd?
(amount of increase/original price) x 100%
Even
11 - 13 - 17 - 19
True

35. What percent of 40 is 22?
Its last two digits are divisible by 4.
10! / 3!(10-3)! = 120
3sqrt4
55%

36. What is a major arc?

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37. Legs: 3 - 4. Hypotenuse?
1
Undefined - because we can'T divide by 0.
5
The empty set - denoted by a circle with a diagonal through it.

38. 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 square of the ratios of the corresponding sides.
Its negative reciprocal. (-b/a)
II
$3 -500 in the 9% and $2 -500 in the 7%.

39. For similar triangles - the ratio of their corresponding sides is 2:3. What is the ratio of their areas?
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Cd
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)
Arc length = (n/360) x pi(2r) where n is the number of degrees.

40. To convert a decimal to a percent...
The overlapping sections.
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)
...multiply by 100.

41. What are the irrational numbers?

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42. What is the 'domain' of a function?
Relationship cannot be determined (what if x is negative?)
A subset.
I
The set of input values for a function.

43. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
G(x) = {x}
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.
67 - 71 - 73
4725

44. 40 < all primes<50
41 - 43 - 47
y = (x + 5)/2
Sqrt 12
55%

45. What are the smallest three prime numbers greater than 65?
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
67 - 71 - 73
83.333%
Its negative reciprocal. (-b/a)

46. What is the ratio of the sides of an isosceles right triangle?
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)
Yes. [i.e. f(x) = x^2 - 1
1:1:sqrt2
(a - b)(a + b)

47. What is the percent formula?
x= (1.2)(.8)lw
Part = Percent X Whole
130pi
500

48. What is the set of elements found in both A and B?
441000 = 1 10 10 10 21 * 21
Move the decimal point to the right x places
x^(6-3) = x^3
The interesection of A and B.

49. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
No - only like radicals can be added.
6
F(x) + c
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

50. 10^6 has how many zeroes?
6
The set of elements which can be found in either A or B.
12.5%
28. n = 8 - k = 2. n! / k!(n-k)!