Question:
Four unbiased coins are tossed simultaneously. Probability of getting at most two heads is ________.
Four unbiased coins are tossed simultaneously. Probability of getting at most two heads is ________.
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"At most 2" means 0, 1, or 2.
Updated On: Jun 26, 2026
- $\frac{5}{8}$
- $\frac{9}{16}$
- $\frac{11}{16}$
- $\frac{13}{16}$
- $\frac{15}{16}$
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The Correct Option is C
Solution and Explanation
Step 1: Concept
Use the binomial distribution $P(X=r) = ^nC_r p^r q^{n-r}$.
Step 2: Meaning
Total outcomes $= 2^4 = 16$.
Step 3: Analysis
At most 2 heads $= P(0) + P(1) + P(2) = ^4C_0 + ^4C_1 + ^4C_2 = 1 + 4 + 6 = 11$.
Step 4: Conclusion
Probability $= 11/16$. Final Answer: (C)
Use the binomial distribution $P(X=r) = ^nC_r p^r q^{n-r}$.
Step 2: Meaning
Total outcomes $= 2^4 = 16$.
Step 3: Analysis
At most 2 heads $= P(0) + P(1) + P(2) = ^4C_0 + ^4C_1 + ^4C_2 = 1 + 4 + 6 = 11$.
Step 4: Conclusion
Probability $= 11/16$. Final Answer: (C)
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