Question

Black coat colour in Labrador Retrievers is produced by the dominant B allele. Brown labs are homozygous recessive (bb). Duke, a black male, whose mother was brown, is mated with Shadow, a black
female, who in a previous mating with another father produced brown offspring. What is the probability
that when Duke and Shadow are mated…

a. Their first pup is brown?

b. They have 3 male pups and at least one is black?

c. They have 3 black pups (regardless of sex)?

Please help me, I have answers but I am completely unsure if they are right. My answers are a)1/4 chance, b) 7/8 chance, and c)3/4. Please show how you get your answers so I know what I am doing wrong. Please and thank you

Answer 1

From your data, both dogs are Bb. Using a Punnett square, there is a 25% chance of having a brown (bb) offspring.

2. What does gender have to do with it?

3. There is .75 or 3/4 probability of any one pup being Black (Bb or BB). Probability of all events occurring is found by multiplying the probability of the individual events.
.75 * .75 * .75 = ?

Answer 2

for number two you gave to calculate the probability of only 3 male offsprings being born and the probability of at least one being black.