Math Flashcards

1
Q

Leona bought a 1 year, $10,000 certificate of deposit that paid interest at an annual rate of 8% compounded semiannually.

A

2 payments in one year, each half of the annual rate. Two payments of 4% interest rate

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2
Q

5/4

A

1.25

125%

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3
Q

7/4

A

1.75

175%

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4
Q

1/8

A
  1. 125

12. 5%

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5
Q

3/8

A
  1. 375

37. 5%

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6
Q

5/8

A
  1. 625

62. 5%

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7
Q

7/8

A
  1. 875

87. 5%

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8
Q

2/3

A
  1. 6666

66. 6%

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9
Q

1/6

A
  1. 16666

16. 7%

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10
Q

5/6

A
  1. 833

83. 3%

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11
Q

1/9

A
  1. 111

11. 1%

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12
Q

Convert a decimal to a fraction

A

Put the digits to the right of the decimal point. Over the appropriate power of 10. Simplify.

0.036 = 36/1000

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13
Q

Convert a percent to a fraction

A

Write over 100

OR

Convert to a decimal first then convert decimal to fraction
3.6% = 0.036 = 36/1000 = 9/250

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14
Q

Percent change of an original percent

A

% change = change in value/original value

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15
Q

New percent of an original percent

A

New % = new value /original value

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16
Q

Percent INCREASE of 10%

A

110%

Or 1.1

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17
Q

Percent increase of 20%
Percent increase of 25%
Percent increase of 50%

A

120% or 1.2 or 6/5
125% or 1.25 or 5/4
150% or 1.5 or 3/2

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18
Q

Percent DECREASE of 10%

A

90% or 0.9

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19
Q

Percent decrease of 20%
Percent decrease of 25%
Percent decrease of 50%
Percent decrease of 75%

A

80% or 0.8 or 4/5
75% or 0.75 or 3/4
50% or 1/2
25% or 1/4

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20
Q

If you have a variable in an exponent or exponents…

Example: 3^x = 27^4

A

Make the bases equals usually by breaking the given bases down to primes.

3^x = 27^4
3^x = (3^3)^4
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21
Q

“Each worker on the night crew loaded 3/4 as many boxes as each worker on the day crew.”

A

As many = of

Can multiply
3/4x

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22
Q

Fractions/decimals (0-1) decrease and exponents increase

A

Because denominator increases.

(1/2)^2= 1/4

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23
Q

Pay attention to the parentheses with exponents (PEMDAS)

A

-2^4=-16

(-2)^4=16

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24
Q

When multiplying exponents with same base = ADD

When dividing exponents with the same base = SUBTRACT

A

x^15/x^8 = x^7

2^2 x 2^3 = 2^5

*when simplifying or solving try to get to the same base!

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25
Nested exponents = when you raise an exponential term to an exponent, multiply the exponents
(a^5)^4 = a^20
26
Raise a fraction to a negative power = raise reciprocal to the equivalent positive power
(3/7)^-2 = (7/3)^2
27
1.4^2
2
28
1.7^2
3
29
2.25^2
5
30
12^2
144
31
13^2
169
32
14^2
196
33
15^2
225
34
16^2
256
35
25^2
625
36
2^3
8
37
3^3
27
38
4^3
64
39
5^3
125
40
2^4 | 4^2
16
41
2^5
32
42
2^6 | 4^3
64
43
2^7
128
44
2^8 | 4^4
256
45
2^9
512
46
2^10 | 4^5
1024
47
3^4
81
48
0=0 (combo algebra problem)
True statement, same line = infinite many solutions
49
0=5 (combo algebra)
False statement (i.e. Parallel lines, No solutions)
50
Square of a sum
(X+y) ^2 = x^2 + 2xy + y^2
51
Square of a difference
(X-y)^2 = x^2 - 2xy + y^2
52
Differences of squares
(X+y) (x-y) = x^2 - y^2
53
Average rate
Because the object spends more time traveling at the slower rate, the average rate will ALWAYS be closer to the SLOWER of the two rates.
54
Average speed
Average speed = total distance/total time
55
Relative Rates
1. Bodies move toward each other (r1 + r2) 2. Bodies move away from each other (r1+ r2) 3. Bodies move in the same direction on the same path. (r1-r2)
56
Counting integers (if both extremes need to be added)
(Last - First) + 1
57
Counting consecutive multiples, if extremes are included
(Last - First) / increment + 1 The bigger the increment the smaller the result
58
Properties of evenly spaced sets (ALL evenly spaced sets)
1. Mean and median are equal to each other Ex: mean if 4, 8, 12, 16, 20? Mean = 12 and median = 12 2. Mean and median of the set are equal to the average of the FIRST and LAST terms. (First + last)/ 2
59
Sum of consecutive integers
Sum = average x number of terms Average of an odd number of consecutive integers will always be an integer. Average of an even number of consecutive integers will never be an integer.
60
Triangle properties
Sum of 2 side lengths will always be greater than the third side length. Any side is greater than the difference of the other 2 side lengths. All angles = 180 Sides correspond with angles: the largest angle is opposite the longest side.
61
Right triangles (and triples)
A^2 + B^2 = C^2 3: 4:5 5: 12:13 8: 15:17
62
Sum of interior angles of a polygon
(n-2) x 180
63
Area of a Trapezoid
(Base 1 + Base 2) x Height/2
64
45: 45:90 triangle 30: 60:90 triangle
45: 45:90 x: x : x root2 30:60:90 x : x root 3 : 2x
65
Similar triangles
If all corresponding angles are equal AND corresponding sides are in proportion, triangle is similar.
66
Inscribed Angle
Inscribed angle: has its vertex on the circle itself Inscribed angle is equal to half of the angle of the arc it intercepts.
67
Inscribed triangle
Inscribed triangle: if all of the vertices of the triangle are points on the circle ** RULE: if one of the sides of an inscribed triangle is the diameter of the circle, triangle must be a right triangle.
68
Divisibility Rules: 3 and 9
If the sum of the integer's digits is a multiple of 3 - divisible by 3 If the sum of the integer's is a multiple of 9 - divisible by 9
69
Prime numbers
2, 3, 5, 7, 11, 13, 17, 19 1 is NOT a prime number (only divisible by itself) 2 is the only even prime number
70
Divisibility rules: 4 Divisibility rules: 8
If the last two numbers are divisible 4. Example: 23,456 because 56 is divisible by 4 25,678 not because 78 not divisible by 4. If the last three numbers are divisible by 8.
71
Divisibility rules: 6
If the integer is divisible by both 2 and 3. 48/2 AND. 48/3
72
Addition/Subtraction Odd Even Rules
Even +/- Even = Even Odd +/- Odd = Even Even +/- Odd = Odd
73
Multiplication Odd/Even Rules
Even x Even = Even Even x Odd = Even Odd x Odd = Odd
74
Average of consecutive integers
(First + last)/2 Average of first and last term
75
Integer m has an odd number of positive factors
Odd number of factors = perfect square