Notes, summaries, assignments, exams, and problems for Mathematics

Frequency Tables for Data Organization

A frequency table is the easiest way to organize data. To construct a frequency table from the data, essentially we have to count how many times each event occurs among the data. Depending on the type of variable, we can add more or less information to the frequency table.

• Absolute frequency: Count how many times each value appears in the table.
• Relative frequency: Count how many times each value appears in the table, divided by the size of the sample.
• Cumulative absolute frequency: The sum of all previous absolute frequencies (e.g., how many people own 3 cars or less?).
• Cumulative relative frequency: The sum of all previous relative frequencies (e.g., what proportion of people own 3 cars or less?).

Discrete

Visualizing Discrete and Continuous Data

We can use bar charts to describe data from a discrete variable. In this case, we can perform additional analysis: first, create a frequency table, then draw the charts.

Cumulative Bar Charts

In addition to the standard bar chart, we can draw a cumulative bar chart:

• The standard bar chart allows for comparison among groups.
• The cumulative bar chart displays percentages.
• Note: Cumulative bar charts require an inherent order among outcomes, so they are not suitable for categorical variables.

Histograms for Continuous Variables

Histograms are the equivalent of bar charts for continuous variables:

• To draw a histogram, you must first group the data, similar to building a frequency table.
• Key Difference: In a histogram,

MONEY

Budgeting and Expenses

• Budget: A plan for how to spend money.
• Grant: Money given by the government for a particular purpose, often education.
• Loan: Money borrowed from a bank or other lender, usually with interest.
• Fee: Money paid for a professional service (e.g., lawyer, consultant).
• Fare: Money paid to travel by bus, train, taxi, etc.

Savings and Investments

• Savings: Money set aside for future use.
• Donation: Money given to a charity or other organization.
• Deposit: A portion of a larger payment made upfront.
• Will: A legal document that specifies how a person's assets will be distributed after their death.
• Lump sum: A single payment of a large amount of money.

Financial Terms

• Fine: Money paid as a penalty for breaking a rule or law.
• Installment: A

Decision Making and Problem Solving

Defining the Process

Problem Solving: Identifying the difference between the actual and desired state of affairs, and taking action to resolve the difference.

Decision Making: Defining the problem, identifying alternatives, determining criteria, evaluating alternatives, and choosing an alternative.

Types of Decision Problems

Single-Criterion Decision Problem: Finding the best solution based on one criterion.

Multicriteria Decision Problem: Finding the best solution considering multiple criteria.

Key Concepts in Decision Making

Decision: The selected alternative.

Model: A representation of a real object or situation.

• Iconic Model: A physical replica of a real object.
• Analog Model: A physical representation, but doesn'

Probability Distributions

Discrete Random Variables

1. If the outcomes of a discrete random variable follow a Poisson distribution, then which of the following is true?
   • (A) The mean equals the variance.
2. Which of the following is not a characteristic of a binomial probability distribution?
   • (A) Each trial has a finite number of possible outcomes.
3. If the probability of a machine producing a defective part is 0.05, what is the probability of finding exactly 5 defective parts from a sample of 100? (Assume that the process follows a binomial distribution and round the answer to four places.)
   • (C) 0.1800
4. The number of arrivals of delivery trucks per hour at a loading station is an example of which of the following processes?
   • (C) Poisson
5. When sampling without replacement

Standard Form/Scientific Notation

If you had a number like this:

54300000.0

Then you would have to make the number so it is under 10:

5.4300000

But you moved the decimal place 7 places to the left, so the standard form is:

5.43 x 10⁷

HINT

Recurring decimals are written with a little dot or a line above a number to show that it goes on forever.

HINT

Terminating decimals are decimals that eventually stop and are not recurring.

Rounding

When rounding, you round to the nearest number with the amount of decimal places provided. For example:

59.54

The critical digit (last number) determines what the number will be. In this example, the critical digit is 4. 4 or less, let it rest. 5 or more, raise the score. So because the critical digit is 4, you would round the... Continue reading "Decimals, Fractions, and Percentages" »

Financial Concepts and Calculation Practice

Expectation Theory and Two-Year Rates

Problem: If the one-year rate on an instrument is 9.0% and the expected rate for a one-year instrument one year from today is 9.89%, what is the expected two-year rate today, if the expectation theory holds?

• One-year rate: 9.00%
• One-year rate, one year forward: 9.89%

Formula: (1 + R1) * (1 + ER2) = (1 + R2)^2

Calculation:

• (1 + 0.09) * (1 + 0.0989) = (1 + R2)^2
• (1.09) * (1.0989) = (1 + R2)^2
• 1.197801 = (1 + R2)^2
• sqrt(1.197801) = 1 + R2
• 1.094449 = 1 + R2
• R2 = 0.094449

Expected Two-Year Rate: 9.44% (approximately 9.4%)

Understanding the Rule of 72

The Rule of 72 is a quick method to estimate the number of years it takes for an investment to double in value, given a fixed annual... Continue reading "Essential Financial Concepts & Calculations" »

Which of the following is most likely an issuer bonds: HEDGE FUND

A bond issued by a city would most likely be classified as a: NON-SOVEREIGN GOVERNMENT BOND

A fixed-income security issued with a maturity at issuance of nine months is most likely classified: MMSECURITY

The price of a bond issued in the US by a British company and denominated in US dollars is most likely: CHANGE AS US INTEREST RATES CHANGE

Interbank offered rates are best described as the rates at which major banks can: BORROW UNSECURED FUNDS

A company issues floating-rates bonds. The coupon rates is expressed as the three-month Libor plus a spread. The coupon payments are most likely: LIBOR INCREASES

A 10-year bond was issued four years ago. The bond is denominated in US dollars,

Taylor Series

f(x+h) = f(x) + f'(x)h + f''(x)h² /2! + f'''(x)h³ /3! + ...

Secant Method (Find Root)

1. Rewrite as f(x)=0
2. Set initial points
3. f'(x₂) = (f(x₂) - f(x₁)) / (x₂-x₁)
4. New point becomes x₂
5. Iterate

LU Decomposition

A = LU

Crout's

Identity top

Doolittle

Identity bottom

1. Set up LU
2. Find components through matrix multiplication and solve for variables

Solving for b matrix

LUX=B

1. Set UX = Y
2. Solve LY = B using algebra
3. Solve UX = Y using algebra

Norm

Absolute value of the largest row sum

Condition

||A||_inf||A^-1||_inf

Gauss-Seidel

1. Set each equation to a variable
2. Use any initial values for the first equation
3. Use the x₁ from the first equation to solve x₂
4. Iterate (Fast version of Jacobi Method)

Discrete Least Squares Approximation

AX = B

1. Make matrix A by [ n ∑(x) ∑(x²) ...]
2. Make