If a couple has four boys, the probability of fifth child being male is

Options

A. `50%`
B. `25%`
C. `75%`
D. `100%`

Answer

To solve the question of the probability of the fifth child being male after a couple has already had four boys, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Genetic Determination of Sex**:
- In humans, sex is determined by the combination of sex chromosomes. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).

2. **Gamete Production**:
- The mother (XX) can only produce X gametes.
- The father (XY) produces two types of gametes: X and Y. Each type has an equal probability of 50%.

3. **Probability Calculation**:
- The sex of each child is independent of the previous children. This means that the outcome of one child does not affect the outcome of another.
- For each child, the probability of being male (XY) is 50% (or 0.5) and the probability of being female (XX) is also 50% (or 0.5).

4. **Conclusion**:
- Therefore, regardless of the fact that the couple has had four boys, the probability of the fifth child being male remains 50%.

### Final Answer:
The probability of the fifth child being male is **50%**.

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