If the probability of a male birth is 0.5 and the probability of a female birth is 0.5, what is the probability of a family having two children, both girls?

Consider a population growing exponentially. If the population doubles every 25 years, approximately how many years will it take for the population to increase by a factor of 8?

Suppose a species has two alleles for a certain trait, A and a. If 84% of the population carries at least one copy of the dominant allele 'A' and the population is in Hardy-Weinberg equilibrium, approximately what percentage of the population carries two copies of the recessive allele 'a'?

In a population, the birth rate is 3% and the death rate is 1%. What is the approximate doubling time of the population (in years)? (Use the Rule of 70)

A study shows a correlation coefficient of r = -0.8 between the number of contraceptive methods used and the number of unplanned pregnancies. What does this indicate?