Maths · Probability: Probability of an event, addition and multiplication theorems of probability
Out of 800 families with 4 children each, the expected number of families having
Out of 800 families with 4 children each, the expected number of families having 2 boys and 2 girls
- A. 100
- B. 200
- C. 300
- D. 400
Step-by-step solution
Assuming equal probability of a child being a boy or a girl (1/2 each) and independent births, the number of families with 2 boys and 2 girls follows a binomial distribution. Probability of exactly 2 boys in 4 children = C(4,2)*(1/2)^4 = 6/16 = 3/8. Expected number of families = 800 * 3/8 = 300.
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