Quiz 2
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Chatty · Quiz 2 prep system (overview)

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8 min read
2026-08-16

Reading compass

Now · A. Mathematics for Data Science I

1. The system we're going to use

For every concept, I'll eventually classify it through this ladder:

Layer A — Concept

What is the thing?
Example: conditional probability.

Layer B — Notation / representation

How does IITM represent it?
P(AB)=P(AB)P(B)P(A\mid B)=\frac{P(A\cap B)}{P(B)}

Layer C — Recognition

How do I know this is a conditional-probability problem?
This is extremely important for Quiz 2.

Layer D — Pattern

What recurring problem structure does it belong to?
"Given that something has already happened, find the probability of another event."

Layer E — Procedure

What exact sequence do I execute?

Layer F — Variations

What happens if the question changes slightly?

Layer G — Traps

Where does IITM try to make you make a stupid mistake?

Layer H — Difficulty

  • Easy: direct recognition/application
  • Medium: multiple concepts or transformation
  • Hard: unfamiliar wording, indirect reasoning, multi-step composition

Layer I — Generalization

Can you solve a whole family of questions rather than memorizing one answer?

Layer J — Independent retrieval

You solve it without my help.
That last layer matters. I don't want to turn you into someone who can recognize my explanations but cannot solve the question themselves.

2. Canonical Quiz 2 syllabus

A. Mathematics for Data Science I

The official syllabus gives Weeks 1–8 as follows. turn1view0

Concepts

  • Polynomial expressions
  • Addition
  • Subtraction
  • Multiplication
  • Division
  • Polynomial algorithms
  • Roots / xx-intercepts
  • Multiplicity
  • End behaviour
  • Turning points
  • Polynomial graphing
  • Constructing polynomials

Pattern families

Easy
  • Add/subtract polynomials.
  • Multiply.
  • Evaluate polynomial.
  • Identify degree.
  • Identify leading coefficient.
Medium
  • Polynomial division.
  • Factorization.
  • Roots → polynomial.
  • Polynomial → graph characteristics.
Hard
  • Multiplicity + graph behaviour.
  • Determine unknown coefficients from constraints.
  • Reconstruct polynomial from roots/points.
  • Reason about end behaviour without fully expanding.

Important mental model

A polynomial isn't merely:
"some algebraic expression."
Think of it simultaneously as:
expressionequationfunctiongraph\text{expression} \leftrightarrow \text{equation} \leftrightarrow \text{function} \leftrightarrow \text{graph}
Quiz questions can move between those representations.

5. Maths Week 5 — Functions

Official topics include horizontal/vertical line tests, exponential functions, composite functions and inverse functions. turn1view0

Concepts

Definition:
logbx=y    by=x\log_b x=y\iff b^y=x
Properties:
logb(xy)=logbx+logby\log_b(xy)=\log_bx+\log_by
logb(xy)=logbxlogby\log_b\left(\frac{x}{y}\right)=\log_bx-\log_by
logb(xk)=klogbx\log_b(x^k)=k\log_bx
Change of base:
logbx=logaxlogab\log_bx=\frac{\log_ax}{\log_ab}

Patterns

  1. Evaluate logs.
  2. Simplify logarithmic expressions.
  3. Convert log ↔ exponential form.
  4. Solve exponential equations.
  5. Solve logarithmic equations.
  6. Determine whether a solution is valid.
  7. Interpret logarithmic graphs.

Major trap

Whenever you manipulate logarithmic equations, domain restrictions matter.
You cannot blindly accept algebraic solutions.

7. Maths Week 7 — Sequences, Limits & Continuity

Officially this week introduces functions of one variable, graphs/tangents, limits for sequences and functions, and continuity. turn1view0

Core object

f(x)f'(x)
Interpretations:
  • instantaneous rate of change
  • slope of tangent
  • local behaviour

Patterns

Derivative computation

Apply appropriate rules.

Tangent

At x=ax=a:
yf(a)=f(a)(xa)y-f(a)=f'(a)(x-a)

Linear approximation

f(x)f(a)+f(a)(xa)f(x)\approx f(a)+f'(a)(x-a)

Critical points

Typically solve:
f(x)=0f'(x)=0
and also consider where ff' is undefined.

Local extrema

Use derivative behaviour around critical points.

L'Hôpital

For appropriate indeterminate forms:
= \lim_{x\to a}\frac{f'(x)}{g'(x)}$$ when the conditions for the rule hold. --- # 9. Computational Thinking This course is particularly important because IITM explicitly describes CT as learning programming concepts through **manual execution**, rather than simply writing code. turn1view2 Patterns: - Variable tracing - State changes - Initialization - Iterating through data - Filtering - Datatype identification - Flowchart interpretation - Detecting invalid/insane input Example abstract pattern: ```text value ← initial_value for each item: update value output value ``` You should eventually be able to look at this and immediately ask: > What is the state? > What changes it? > What remains invariant? > What is the final state? --- # 10. CT Week 2 - Iteration - Filtering - Selection - Pseudocode - Finding maximum/minimum - AND Patterns: ### Accumulation ```text total ← 0 for each x: total ← total + x ``` ### Maximum ```text best ← first item for each x: if x > best: best ← x ``` ### Filtering ```text if condition: keep/process x ``` ### Conjunction $$A\land B$$ Both must be true. --- # 11. CT Week 3 - Multiple non-nested iterations - Three-prizes problem - Procedures - Parameters - Side effects - OR This is where we start thinking in **reusable computational units**. Pattern: $$\text{input}\rightarrow\text{procedure}\rightarrow\text{output}$$ We'll distinguish: - parameter - argument - local state - returned result - side effect And: $$A\lor B$$ means at least one condition is true. --- # 12. CT Week 4 - Nested iterations - Birthday paradox - Binning This is a major pattern jump. Nested loop structure: ```text for each x: for each y: do something ``` Conceptually: $$n\times n$$ potential pairwise interactions. ### Birthday-paradox pattern Not merely a probability question. It's a **pair-generation / collision-detection** pattern. ### Binning Map continuous/discrete values into categories: $$x\rightarrow\text{bin}(x)$$ This idea becomes useful throughout data science. --- # 13. CT Week 5 — Lists Officially: lists and insertion sort. turn1view2 Patterns: ### Table Think: $$\text{row}\times\text{column}$$ ### Dictionary Think: $$\text{key}\rightarrow\text{value}$$ Typical questions: - Lookup - Update - Count frequencies - Map identifiers to information - Represent relationships - Translate table ↔ dictionary representation Frequency counting is a particularly important reusable pattern: ```text for each item: frequency[item] += 1 ``` --- # 15. CT Week 7 — Graphs & Matrices Officially: - Graphs - Matrices. turn1view3turn0search5 And here's where I want to be particularly strict: **CT pattern → Python implementation → Python-specific behaviour.** --- ## Python W1 — Algorithms Concepts: - Python execution model - Variables - Expressions - Values - Types - Assignment - Input/output - Basic algorithmic thinking Patterns: ```python x = ... y = ... z = ... ``` Trace the state after every line. --- # 18. Python W2–3 — Conditionals Core structures: ```python if condition: ... elif condition: ... else: ... ``` Patterns: ### Binary decision $$P\rightarrow A/B$$ ### Multiple mutually exclusive cases $$P_1,P_2,\ldots,P_n$$ ### Compound condition ```python if A and B: ``` ### Alternative condition ```python if A or B: ``` Important distinction: ```python and ``` versus ```python or ``` and nested conditionals. We'll also train **truth-table thinking**, not just syntax. --- # 19. Python W4–5 — Iterations & Ranges Core structures: ```python for x in ...: ``` and ```python while condition: ``` Patterns: - fixed repetition - condition-controlled repetition - counting - accumulation - filtering - searching - maximum/minimum - nested iteration - range generation Important: ```python range(start, stop, step) ``` has an **exclusive stop**. This is one of the classic Python traps. --- # 20. Python W6–8 — Basic Collections This is a large chunk. ### Lists ```python [x1, x2, x3] ``` Patterns: - indexing - traversal - modification - append - insertion - deletion - membership - slicing - aggregation ### Tuples ```python (x, y) ``` Think: > ordered collection with different mutability semantics. ### Dictionaries ```python { key: value } ``` Think: $$key\rightarrow value$$ ### Collection patterns We'll train: - frequency counting - lookup - grouping - transformation - filtering - aggregation - nested collections - iteration over collection structures --- # 21. Statistics for Data Science I Stats is probably the course where **interpretation traps** will matter most. The official Weeks 1–8 are clearly defined. turn1view1 ### Categorical × categorical Contingency tables. ### Numerical × numerical Scatterplot. ### Covariance Conceptually: > Do two variables tend to move together? ### Pearson correlation $$-1\le r\le1$$ Interpret: - sign → direction - magnitude → strength of linear association ### Point-biserial correlation Useful when: - one variable is binary/categorical - one is numerical ### Major trap **Correlation ≠ causation.** And: > $r\approx0$ does not mean "no relationship whatsoever"; it primarily indicates little/no **linear** association. --- # 25. Stats W5 — Counting Concepts: - Addition rule - Multiplication rule - Factorials Factorial: $$n!=n(n-1)(n-2)\cdots1$$ ### Addition rule Use when alternatives are mutually exclusive: $$N=N_1+N_2+\cdots$$ ### Multiplication rule Use for sequential choices: $$N=N_1N_2\cdots$$ The real skill is **recognizing whether a problem is additive or multiplicative**. --- # 26. Stats W6 — Permutations & Combinations Permutation: $$P(n,r)=\frac{n!}{(n-r)!}$$ Combination: $$C(n,r)=\binom nr =\frac{n!}{r!(n-r)!}$$ ### Recognition rule Ask: > **Does order matter?** If yes → permutation-type reasoning. If no → combination-type reasoning. This becomes a major pattern classifier. --- # 27. Stats W7 — Probability Concepts: - Random experiment - Sample space - Event - Probability - Probability properties Core axioms: $$0\le P(A)\le1$$ $$P(S)=1$$ For disjoint events: $$P(A\cup B)=P(A)+P(B)$$ General addition: $$P(A\cup B) = P(A)+P(B)-P(A\cap B)
Complement:
P(Ac)=1P(A)P(A^c)=1-P(A)

Pattern families

  • direct probability
  • complement
  • union
  • intersection
  • mutually exclusive events
  • sample-space counting
  • probability from combinatorics

28. Stats W8 — Conditional Probability

This is probably one of the highest-value Quiz 2 areas.
Concepts:
  • Conditional probability
  • Multiplication rule
  • Independence
  • Law of total probability
  • Bayes' theorem
Definition:
P(AB)=P(AB)P(B)P(A\mid B) = \frac{P(A\cap B)}{P(B)}
Multiplication:
P(AB)=P(AB)P(B)P(A\cap B) = P(A\mid B)P(B)
Independence:
P(AB)=P(A)P(B)P(A\cap B)=P(A)P(B)
or equivalently:
P(AB)=P(A)P(A\mid B)=P(A)
when applicable.
Bayes:
P(AB)=P(BA)P(A)P(B)P(A\mid B) = \frac{P(B\mid A)P(A)} {P(B)}

The pattern we're going to hammer

A question gives you:
evidence BB
and asks:
probability of underlying condition AA.
That is often a Bayesian inversion problem.

Document outline

Keep your place and jump directly to a heading.

Table of Contents
System Normal // Awaiting Context

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