Final answer:
The forked line and probability methods use the product rule when determining the likelihood of specific genetic outcomes in offspring, which involves multiplying the individual probabilities of separate genetic events.
Step-by-step explanation:
The forked line and probability methods in genetics make use of the product rule of probability. This rule is utilized when predicting the genotypic ratios or phenotypic ratios of offspring resulting from a genetic cross. It applies to the independent assortment of alleles for different genes. The product rule states that the probability of two independent events occurring together is the product of their individual probabilities. This is reflected in the phrase "and" when considering the simultaneous occurrence of multiple genetic events.
For example, if you are looking to find the probability of offspring inheriting a dominant allele from one parent and a recessive allele from another, you would multiply the probabilities of each event happening independently. Additionally, the sum rule is used when there are multiple pathways to a single outcome - this rule implies adding the probabilities of each independent event to determine the total probability of an occurrence.