# bio

posted by
**Hela**
.

a brown mouse is crossed with hertozygous black mouse. if the mother has a litter of four, what are thae chances all of them will be brown?

http://en.wikipedia.org/wiki/Punnett_square

do you have more specifics? because that didn't help a bit

There is a 50% chance the the litter will be brown.

Assuming that the heterozygous mouse has one recessive brown gene (b) and one dominant black gene (B) and the brown mouse is bb, **Kyonia** is right *for one birth*.

Thus the brown mouse can give either b or b, while the black mouse can give either b or B. Plug the symbols into the Punnett square to see how we arrived at the conclusion.

However, the question asked for the probability that **all** of them are brown. To find the probability that *all* events will occur, you need to *multiply* the probability of the individual events, in this case, the 4 mice. You can do the calculations.

I hope this helps. Thanks for asking.