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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. What is a tangent?
A tangent is a line that only touches one point on the circumference of a circle.
x(x - y + 1)
90
A grouping of the members within a set based on a shared characteristic.

2. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
0
48
An isosceles right triangle.
A grouping of the members within a set based on a shared characteristic.

3. What are 'Supplementary angles?'
6 : 1 : 2
Two angles whose sum is 180.
The shortest arc between points A and B on a circle'S diameter.
Divide by 100.

4. 8.84 / 5.2
1/a^6
...multiply by 100.
1.7
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.

5. What are congruent triangles?
4a^2(b)
Triangles with same measure and same side lengths.
II
5 OR -5

6. A number is divisible by 6 if...
Its divisible by 2 and by 3.
A reflection about the axis.
Divide by 100.
4096

7. If an inequality is multiplied or divided by a negative number....
The direction of the inequality is reversed.
31 - 37
A = I (1 + rt)
83.333%

8. 10<all primes<20
500
The sum of its digits is divisible by 3.
37.5%
11 - 13 - 17 - 19

9. The perimeter of a square is 48 inches. The length of its diagonal is:
3/2 - 5/3
12sqrt2
2 & 3/7
Two angles whose sum is 90.

10. 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?
500
A = I (1 + rt)
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
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.

11. x^2 = 9. What is the value of x?
Yes - like radicals can be added/subtracted.
(a + b)^2
A reflection about the axis.
3 - -3

12. Which quandrant is the lower right hand?
The point of intersection of the systems.
(a - b)(a + b)
IV
41 - 43 - 47

13. Simplify 4sqrt21 X 5sqrt2 / 10sqrt7
2sqrt6
y = 2x^2 - 3
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
27^(-4)

14. To convert a decimal to a percent...
...multiply by 100.
F(x) - c
(p + q)/5
10! / (10-3)! = 720

15. What is the formula for compounded interest?
31 - 37
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.
The set of output values for a function.
2(pi)r^2 + 2(pi)rh

16. What is a parabola?
The direction of the inequality is reversed.
130pi
Ax^2 + bx + c where a -b and c are constants and a /=0
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.

17. 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?
A reflection about the origin.
Area of the base X height = (pi)hr^2
9 : 25
Move the decimal point to the right x places

18. Simplify the expression (p^2 - q^2)/ -5(q - p)
y = 2x^2 - 3
F(x) - c
(p + q)/5
N! / (k!)(n-k)!

19. What is a central angle?
A central angle is an angle formed by 2 radii.
Angle/360 x 2(pi)r
(a + b)^2
Its negative reciprocal. (-b/a)

20. If the two sides of a triangle are unequal then the longer side...
Yes. [i.e. f(x) = x^2 - 1
A reflection about the origin.
Lies opposite the greater angle
Angle/360 x 2(pi)r

21. 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)
A set with a number of elements which can be counted.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
500

22. 1/6 in percent?
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
The set of elements found in both A and B.
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)
16.6666%

23. The slope of a line perpendicular to (a/b)?
I
Its negative reciprocal. (-b/a)
2 & 3/7
An isosceles right triangle.

24. What is the sum of the angles of a triangle?
A set with no members - denoted by a circle with a diagonal through it.
...multiply by 100.
180 degrees
(p + q)/5

25. Legs 6 - 8. Hypotenuse?
Infinite.
10
1/a^6
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)

26. What is the 'Solution' for a system of linear equations?
2
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
The point of intersection of the systems.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

27. 6w^2 - w - 15 = 0
The objects within a set.
6
2.592 kg
3/2 - 5/3

28. What are complementary angles?
A tangent is a line that only touches one point on the circumference of a circle.
Area of the base X height = (pi)hr^2
Two angles whose sum is 90.
Factors are few - multiples are many.

29. 40 < all primes<50
12sqrt2
An arc is a portion of a circumference of a circle.
41 - 43 - 47
4a^2(b)

30. Formula for the area of a circle?
2
A = I (1 + rt)
4a^2(b)
A = pi(r^2)

31. What is the graph of f(x) shifted downward c units or spaces?
F(x) - c
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
3 - -3
y = (x + 5)/2

32. Define a 'monomial'
An expression with just one term (-6x - 2a^2)
A chord is a line segment joining two points on a circle.
Angle/360 x 2(pi)r
13

33. 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?
4.25 - 6 - 22
N! / (n-k)!
37.5%
72

34. If Madagascar'S exports totaled 1.3 billion in 2009 - and 4% came from China - what was the value in millions of the country'S exports to China?
20.5
... the square of the ratios of the corresponding sides.
Angle/360 x (pi)r^2
52

35. (12sqrt15) / (2sqrt5) =
4096
10! / 3!(10-3)! = 120
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
Pi is the ratio of a circle'S circumference to its diameter.

36. What is an isoceles triangle?
180 degrees
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 equal sides and two equal angles.
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)

37. What is the measure of an exterior angle of a regular pentagon?
The sum of its digits is divisible by 3.
72
C = 2(pi)r
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)

38. a^2 - b^2 =
0
(a - b)(a + b)
(base*height) / 2
Yes - like radicals can be added/subtracted.

39. How to find the diagonal of a rectangular solid?
10! / 3!(10-3)! = 120
(base*height) / 2
The direction of the inequality is reversed.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

40. 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
No - only like radicals can be added.
(a - b)(a + b)
441000 = 1 10 10 10 21 * 21

41. A number is divisible by 4 is...
Its last two digits are divisible by 4.
3 - -3
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
A reflection about the axis.

42. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
(amount of increase/original price) x 100%
Ax^2 + bx + c where a -b and c are constants and a /=0
4725
6

43. P and r are factors of 100. What is greater - pr or 100?
The set of output values for a function.
The steeper the slope.
... the square of the ratios of the corresponding sides.
Indeterminable.

44. 10^6 has how many zeroes?
The steeper the slope.
6
4725
9 : 25

45. What is the graph of f(x) shifted right c units or spaces?
12.5%
F(x-c)
Undefined - because we can'T divide by 0.
67 - 71 - 73

46. What are the rational numbers?
Yes. [i.e. f(x) = x^2 - 1
A set with a number of elements which can be counted.
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
61 - 67

47. Number of degrees in a 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)
A set with no members - denoted by a circle with a diagonal through it.
180
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

48. Evaluate 3& 2/7 / 1/3
A subset.
4725
Indeterminable.
9 & 6/7

49. Area of a triangle?
All numbers multiples of 1.
(base*height) / 2
(a + b)^2
The direction of the inequality is reversed.

50. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
The objects within a set.
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
2(pi)r^2 + 2(pi)rh
3