CA Foundation · Quantitative Aptitude · Theoretical Distributions
A fair coin is tossed 8 times. What is the probability of getting exactly 3 heads?
The probability is 7/32. Using the binomial formula, P(X = 3) = 8C3 × (1/2)^3 × (1/2)^5 = 56/256, which simplifies to 7/32. The value 5/16 corresponds to exactly four heads, not three.
- A7/32Correct
- B3/8
- C1/8
- D5/16
Explanation
P = 8C3 × (1/2)^8 = 56/256 = 7/32. Option 3/8 is not right because it ignores the binomial coefficient. Option 5/16 is 70/256, the probability of exactly 4 heads.
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