Question

What is the probability of having a girl child in sixth pregnancy if the first five progenies are boys?

(a) 25%

(b) 50%

(c) 65%

(d) 10%

I had been asked this question in an interview for job.

My doubt stems from Inheritance and Variation Principles topic in section Principles of Inheritance and Variation of Biology – Class 12

Answer 1

Right answer is (b) 50%

The best explanation: The probability of having a girl child in the sixth pregnancy, where the first five progenies were male is 50%. As humans show XY type of male heterogamety, where 50% sperms carry 22+ X chromosomes and the other 50% carry 22+Y chromosomes, therefore in each pregnancy there is 50% probability of either a male or a female child.