Question

Solve the following?: Using the punnet square between two organisms with genotype Ff and Ff, the probabilities for the genotype of the offspring is like the following: FF=25%, Ff=50%, ff=25% (continued on details)

If there were 4 offspring from the two organisms, what is the probability that there are 3 ff?

Answer 1

`3/64`

Explanation:

the probability of having an ff genotype is `25%`.

if there are `4` offspring, numbered `1-4`, the ff offspring could be:

`1,2,3`
`1,2,4`
`1,3,4`
`2,3,4`
where the genotype of the other offspring is Ff

there are `4` possible ways to have `3` ff offspring, with one Ff.#

the probability of having Ff is `50%`.

`25% * 25% * 25% * 50% = 0.25 * 0.25 * 0.25 * 0.5`

which is `0.0078125`

`0.0078125 * 4 = 0.03125`

the ff offspring could also be:

`1,2,3`
`1,2,4`
`1,3,4`
`2,3,4`
where the genotype of the other offspring is FF

the probability of having FF is `25%`

`0.25 * 0.25 * 0.25 * 0.25 = 0.25^4 = 0.00390625`

`0.00390625 * 4 = 0.015625`

`0.03125 + 0.015625 = 0.046875`

or `4.6875%`, `3/64`