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

Key Concepts in Engineering Economics

Engineering Economics is the science dealing with quantitative analysis techniques for selecting the most preferable alternative from several technically viable options.

Fundamental Principles

Four fundamental principles must be applied in all engineering economic decisions:

• The time value of money
• Differential (or incremental) cost and revenue
• Marginal cost and revenue
• The trade-off between risk and reward

Core Terminology Explained

Ethics

A set of principles that guides a decision-maker in distinguishing between right and wrong.

Market Interest Rate

The interest rate quoted by financial institutions, which refers to the cost of money for borrowers or the earnings from money for lenders.

Interest Rate

The cost, or price,

Managerial Decision-Making and Business Analytics

Types of Managerial Decisions

To effectively plan, coordinate, and lead, managers make several types of decisions:

• Strategic Decisions: Address high-level issues and the overall direction of the organization. They define future goals and are long-term and complex.
• Tactical Decisions: Focus on how to achieve the goals and objectives set by the strategy. These are typically made by mid-level management for the medium term.
• Operational Decisions: Pertain to day-to-day operations. They are made by operations managers and are often simple and routine.

The Decision-Making Process (DMP)

A structured approach to decision-making involves several key steps:

1. Identify and define the problem.
2. Determine the criteria

Understanding Bookkeeping

Bookkeeping is the systematic recording of financial transactions of a business in books of accounts on a day-to-day basis.

Objectives of Bookkeeping

• Systematic Record: To keep a complete and permanent record of all business transactions.
• Ascertain Profit or Loss: Helps in finding profit or loss at the end of the accounting period.
• Ascertain Financial Position: Helps in knowing assets and liabilities of the business.
• Legal Evidence: Acts as proof in legal matters.

Advantages of Bookkeeping

• All transactions are properly recorded.
• Management can take better decisions.
• Provides information about profit, loss, assets, and liabilities.
• Makes auditing easier.
• Helps compare past and present performance.

Accounting Fundamentals

Accounting... Continue reading "Bookkeeping and Accounting Fundamentals Explained" »

Handshaking Lemma

In any undirected graph, the sum of the degrees of all vertices is twice the number of edges.

Formula: Σdeg(v) = 2|E|

Euler's Formula for Planar Graphs

For planar graphs, the relationship between vertices (V), edges (E), and regions (R) is defined as:

V - E + R = 2

Sum of Degrees and Odd Vertices

The sum of the degrees of all vertices in any graph is always even because each edge contributes 2 to the total sum. Furthermore, the number of vertices with an odd degree must always be even.

Graphs with No Odd Degree Vertices

If all vertices in a graph have an even degree, the graph is Eulerian, meaning it contains an Eulerian circuit.

Complete Graphs

A complete graph with n vertices, denoted as K_n, has an edge between every pair of distinct... Continue reading "Essential Graph Theory Formulas and Concepts" »

1. Type I and Type II Errors

Type I Error (α): Occurs when a researcher rejects a true null hypothesis (a "false positive").

Type II Error (β): Occurs when a researcher fails to reject a false null hypothesis (a "false negative").

The goal of statistical testing is to minimize both errors simultaneously.

2. Parametric vs. Non-Parametric Statistics

Parametric Tests: These assume data is normally distributed and use interval/ratio scales (e.g., t-test, ANOVA).

Non-Parametric Tests: These are "distribution-free" tests used for nominal/ordinal data or small samples (e.g., Chi-square, Mann-Whitney U).

Parametric tests are generally more powerful if their assumptions are met.

3. Null Hypothesis (H₀) vs. Alternative Hypothesis (H₁)

Null Hypothesis (H₀)

Chapter 1: Understanding Variables

Types of Variables

• Categorical: Smoker (current, former, no)
• Ordinal: Non, light, moderate, heavy smoker (ordered categories)
• Quantitative: BMI, Age, Weight (numerical measurements)

Key Definitions

• Observation: Measurements are made (individual or aggregate).
• Variable: The generic characteristic we measure (e.g., age).
• Value: A realized measurement (e.g., 27).

Chapter 2: Statistical Studies

Surveys: Census and Sampling

• Goal: Describe population characteristics.
• Census: Attempts to reach the entire population (costly, time-consuming).
• Sampling: Uses a sample of the population (allows for inferences, saves time and money).
• Simple Random Sampling: Based on probability.
• Issues with Sampling: Under-coverage, volunteer bias,

Investment Portfolio and CAPM Practice Solutions

• Question 1: Portfolio beta (0.6)
• Question 2: Expected return under CAPM (7%)
• Question 3: Expected return with new allocation (6.5%)
• Question 4: Passive investment strategy (Zero alpha)
• Question 5: Net Asset Value calculation ($50)
• Question 6: Definition of NAV (Market value of assets minus liabilities divided by shares outstanding)
• Question 7: Portion of market risk (64%)
• Question 8: Mutual fund return after expenses (4.5%)
• Question 9: Net Asset Value City Street Fund ($40)
• Question 10: Impact on portfolio value (Decreases to $460 million)
• Question 11: Impact on shares outstanding (Decreases to 9 million)
• Question 12: New NAV after shares sold ($40)
• Question 13: Risk premium for stocks (60%)
• Question 14: Optimal

Common Statistical Biases

• Sampling bias: The sample was not representative of the population.
• Non-response bias: Only 24% returned surveys.

Sampling Techniques

• Simple Random Sampling (SRS): 1) Every member of the population has the same chance of being included (representative). 2) Members are chosen independently.
• Random Cluster Sampling: 1) Divide into smaller geographical sectors. 2) Take an SRS of sectors. 3) Count all samples in sectors and scale appropriately.
• Stratified Random Sampling: 1) Divide population into groups based on criteria like age or income. 2) Perform an SRS of each group and scale appropriately.

Data Variables and Distributions

• Variable Types: Categorical and Numeric (discrete and continuous).
• Relative frequency: Count / sample

Set Difference Calculation

To find the set difference A - B, we identify all elements present in set A but not in set B.

Step-by-Step Subtraction

• Is 1 ∈ B? No. (Keep 1)
• Is 2 ∈ B? No. (Keep 2)
• Is 3 ∈ B? Yes. (Remove 3)
• Is 5 ∈ B? No. (Keep 5)
• Is 7 ∈ B? Yes. (Remove 7)
• Is 8 ∈ B? No. (Keep 8)

The remaining elements from set A are {1, 2, 5, 8}.

Symbolic Logic

In symbolic logic, the word "but" functions like "and," indicating that both conditions occur simultaneously. To write "He is rich but not generous" in symbolic form:

• p: "He is rich"
• q: "He is generous"
• ¬q: "He is not generous"
• ∧: The conjunction operator

Logic Symbol Reference

Logarithm Calculations

To find the value of log 360,... Continue reading "Step-by-Step Solutions for Mathematical Problems" »