Day 8: CFA Level I Probability Basics Study Plan (Quantitative Methods)

Today is a study plan (not official CFA Institute curriculum material) to help you learn probability basics in a practical, test-ready way.

Checklist

• Workspace: Clear your desk; keep only your notes, formula sheet/flashcards, and calculator.
• Materials: 1 notebook page titled “Probability – Rules + Common Traps.”
• Calculator: Set your standard defaults (keep this consistent every day). Practice entering fractions/decimals cleanly.
• Question bank setup: Create a mini-quiz set called “Day 7 Probability” with tags:
• Probability rules
• Conditional probability
• Independence
• Bayes (basic)

Daily Ethics block (15–20 minutes)

Ethics warm-up: Conflicts of interest in everyday life

Restate: Put client/employer interests first; disclose conflicts early and clearly.
Write a 4-line scenario: “A friend asks for ‘sure-shot’ stock tips.” What do you say to avoid misleading them?
Do 5 quick Ethics questions (or 5 short scenario checks). Keep answers in one sentence each.

Main study block (70–90 minutes): Probability fundamentals

Focus on understanding the rules and spotting the keywords that show up in CFA-style questions.

A) Probability language (foundation)

• Random variable vs outcome vs event
• Complement rule: 
• Mutually exclusive events (cannot both happen)

B) Addition and multiplication rules

• Addition rule (general): 
• Mutually exclusive special case: 
• Multiplication rule: 

C) Conditional probability and independence

• 
• Independence test:  (or )
• Common trap: “Independent” is not the same as “mutually exclusive.”

D) Total probability + Bayes (basic intuition)

• Think in “paths” (e.g., different groups that could produce an outcome)
• Bayes’ idea: update your belief when you receive new information
• “Given that…” usually signals conditional probability.

25-question practice target (45–60 minutes)

Timed: aim for ~90 seconds per question.

12 questions: addition/multiplication rules (union/intersection)
6 questions: conditional probability 
2 questions: independence vs mutually exclusive (identify which is which)
5 questions: Ethics warm-up set (or 5 mini scenarios)

After each set of 5 questions: pause for 60 seconds and write the one rule you forgot or misread.

5) Mistake-log prompt (write 1–2 lines per miss)

Use exactly one label per mistake:

• Concept gap
• Formula gap
• Calculator error
• Reading error

(If Ethics errors happen, classify them mainly as Concept gap or Reading error.)

6) Five-question review checkpoint (10 minutes)

Answer without notes:

1. If , what is ?
2. If events are mutually exclusive, what is ?
3. Write the general addition rule for .
4. Write the multiplication rule for .
5. In one sentence: what does “independent” mean in probability?

Tomorrow preview (Day 9) Tomorrow, we move into probability distributions (what mean/variance are telling you, and how to recognize common distribution setups fast).