Question

When 4 fair coins are tossed together what is the probability of getting at least 3 heads?

• A. 1/4
• B. 3/4
• C. 5/16
• D. 3/8

Hint:

Use Pascal's Triangle (1-4-6-4-1) for 4 coins; the last two numbers (4 and 1) represent 3 and 4 heads.

Answer 1

The Correct Option is C

Step 1: Concept
For $n$ coins, total outcomes = $2^n$. Probability of $k$ successes = $^nC_k / 2^n$.

Step 2: Meaning
Total outcomes = $2^4 = 16$. "At least 3 heads" means exactly 3 heads OR exactly 4 heads.

Step 3: Analysis
Ways for 3 heads = $^4C_3 = 4$. Ways for 4 heads = $^4C_4 = 1$. Total favorable ways = $4 + 1 = 5$.

Step 4: Conclusion
Probability = 5/16. Final Answer: (C)