Mrs Gabriel is pregnant. The probability that she will give birth to a girl is 1/2 and with blue eyes is 1/4…

Analyze the question: We want the probability of two things happening together: the baby is a girl AND has blue eyes. Gender and eye colour are treated as independent events.

Concept: For independent events A and B:

P(A and B) = P(A) × P(B)

Solution:

• P(girl) = 1/2
• P(blue eyes) = 1/4

P(girl with blue eyes) = 1/2 × 1/4 = 1/8

Check against the options:

• A (1) would mean it is certain, which is not the case.
• B (3/4) is what you would get by adding 1/2 + 1/4. Adding is for "or" events, not "and" events.
• C (1/8) matches our working.
• D (1/4) is just the blue-eyes probability and ignores the girl condition.

Answer: C. 1/8

Exam tip: Think of the words as signals. "AND" means multiply (independent events). "OR" means add (for mutually exclusive events). Also, the probability of two events happening together can never be larger than either single probability, so 1/8 being smaller than both 1/2 and 1/4 is a good sanity check.