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

4.1 The stages of learning as Dienes
The learning process is a process based on abstraction, generalization and communication. This process of abstraction is to accurately analyze and Dienes identifies six different stages in it:
Stage 1: introduces the individual in the middle => Game Free
2nd stage: review, manipulate, get rules => Structured Games
3rd stage: becoming aware of the common structure to games made
4th stage: representation of the common structure graphically or schematically => Stage representative
5th stage study of the properties of abstract structure, which implies the need to invent a language => Stage symbolic
6th stage: Construction of axioms and theorems => formal Stage
Her pedagogical approach

Cost Classification and Analysis for Business Success

Understanding Cost Classifications

Costs can be classified in several ways, providing different insights for business decision-making:

• Function: Such as the department incurring the cost (e.g., production, administration).
• Type: Categorized as Direct or Indirect costs.
• Behavior: How costs react to changes in output, including Fixed, Variable, and Semi-Variable costs.
• Time: Costs associated with a specific period (e.g., period costs).

Direct Costs (Prime Costs)

Direct Costs are expenses that can be easily and directly related to the production of a specific item or service. They are also known as prime costs. For example, the salaries of employees working directly in a production department or the... Continue reading "Cost Classification, Costing Methods, and Break-Even Analysis" »

Different Approaches to Probability Theory

Three different approaches to probability have evolved, mainly to cater to the three different types of situations under which probability measures are normally sought. In this section, we first explore the approaches through examples of distinct types of experiments. The axioms that are common to these approaches are then presented, and the concept of probability is defined using the axioms.

Consider the following situations marked by three distinct types of experiments. The events that we are interested in, within these experiments, are also given.

Situation 1

Experiment: Drawing a number from among nine numbers (say 1 to 9).

Event: On any draw, number 4 occurs.

Situation 2

Experiment: Administering a particular... Continue reading "Probability Theory: Approaches, Revision, and Random Variables" »

Key Statistical Concepts

Understanding Percentiles

The Xth percentile means X% of the data must fall strictly below it. The percentile of X can be calculated using the formula: (# observations (N - 1) / 2 / N * 100%).

Variance: Population vs. Sample

• The sample variance is the sum of the squared deviations from the mean divided by the number of measurements minus one.
• The population variance is the sum of the squared deviations from the mean divided by the number of measurements.

The Empirical Rule

Also known as the 68-95-99.7 rule, the Empirical Rule states that for a normal distribution:

• Approximately 68% of the measurements will fall within one standard deviation of the mean.
• Approximately 95% of the measurements will fall within two standard deviations

Qualitative Variables

Nominal Variables

Nominal variables are qualitative variables that cannot be ordered in an ascending or descending manner; that is, they cannot be ranked. For example, blood group.

Ordinal Variables

Ordinal variables are variables that can be ordered in an ascending or descending manner; that is, they can be ranked.

Quantitative Variables

Discrete Variables

Discrete variables are variables whose values are obtained by counting.

Continuous Variables

Continuous variables are variables whose values are obtained by measurement using a scale.

Mean

Advantages

• Has many good theoretical properties
• Used as the basis of many statistical tests
• Good summary statistic for symmetrical distribution
• Easy to calculate
• Possible for further algebraic treatment

Disadvantages

• Less

Gestalt Psychology and Its Influence on UI Design

• Gestalt Psychology: An early 20th-century study focusing on the organizing principles of vision. Humans inherently seek patterns, a concept that significantly aids in User Interface (UI) design. For further reading, many visualization books cover this topic extensively.
• Gestalt Psychology: Understanding these innate patterns helps direct attention and organize information effectively. Utilize color and spacing strategically for impactful design.

Psychophysical Laws in Perception

• Weber's Law: States that the just-noticeable difference between two stimuli is proportional to their magnitude. This indicates that human perception operates based on percentage increases.
• Steven's Power Law: Describes the

Hypothesis Testing

Statistical Test Selection

1. If the population standard deviation is unknown and the sample size is less than 30: t-test

2. If the population standard deviation is known and the sample size is less than 30: t-test

7. Hypothesis test on population mean; n = 25; σ = 2.5: z-test

8. Hypothesis test on population mean; n = 50; s = 7.2: z-test

18. Test statistic for sample size above 30: z-test

19. Test statistic when population standard deviation is known: z-test

20. Test statistic when population standard deviation is unknown: t-test

21. When to use the t-test: I and II

24. Optimal sample size for z-test: Equal to or larger than 30

Hypotheses and Significance

3. H₀: μ = 30

4. H₁: μ > 30

5. No

9. False: The alternative hypothesis typically... Continue reading "Hypothesis Testing: A Concise Statistical Method Reference" »

Question 1: Decimal Representation of a Fraction

Question: Consider the fraction 6/7. The decimal representation of this fraction is:

Answer: 6 ÷ 7 = 0.857142857... (repeating)

Question 2: Vaccinated to Unvaccinated Ratio

Question: If 60% of a population is vaccinated, what is the ratio of vaccinated to unvaccinated individuals?

Answer: 60% vaccinated → 60 : 40 → Simplified = 3 : 2

Question 3: Property Tax Calculation

Question: A property has been assessed at $225,000. The mill rate is 14.5. To find the property tax, you would multiply the assessed value by:

Answer: The mill rate of 14.5 means $14.50 per $1,000 of assessed value. To convert this to a decimal factor, divide by 1,000:

• 14.5 ÷ 1,000 = 0.0145
• Property tax = $225,000 × 0.0145 = $3,262.

De Morgan's Law

De Morgan's Law: (Flip if the union is true)

, image of set: [min, max]; one-to-one: horizontal line test; Onto: Image must equal domain; Bijective: one-to-one and Onto

|| EV

||

Possible Outcomes and Probability Calculations

• Repetition formula: n^k
  • Example: 5 awards (k) and 30 students (n), with no limit to awards per student.
• Permutation formula: P(n, k) = n! / (n - k)!
  • Example: Each student gets 1 award, so the number of students decreases by one each award.
• No overlap probability: P(n, k) / repetition formula
• Arrangements: a = slots → a! can be multiplied by arrangements within slots
• Die sum probability:
  • List combinations that lead to the sum for each die.
  • If a die is rolled multiple times, each combination has (rolls)! permutations.
  • Add