Conditional probabilitiesBMJ 2009; 338 doi: https://doi.org/10.1136/bmj.b113 (Published 15 January 2009) Cite this as: BMJ 2009;338:b113
- John Fletcher, clinical epidemiologist
- 1BMJ, London WC1H 9JR
Mike has only two children, and they are called Pat and Alex, which could equally be boys’ or girls’ names. In fact, Pat is a girl. What is the probability that Alex is a boy?
b Slightly less than 50%
c Slightly more than 50%
d Between 60% and 70%
e Between 40% and 30%
d—Although this could be …
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