In the cross Ss x Ss what is the probability of three offspring all having long hair? in fraction form

Answer 1

Answer = 1/64. See below for explanation.

Key Facts/Assumptions:

Short hair (S) is dominant

Long hair (s) is recessive

The Punnet Square yields:

SS = 1/4

Ss = 2/4

ss = 1/4

Because only the ss genotype results in long hair phenotype, the probability of ONE offspring having long hair is 1/4.

To calculate the probability of multiple independent events (i.e. multiple offspring with long hair), simply multiply the probabilities of each event. In this question, this is...

P_offspring1 x P_offspring2 x P_offspring3 = Total Probability of having 3/3 offspring with long hair phenotype.

1/4 x 1/4 x 1/4 = 1/64