Question 857657
Here are the possible outcomes:
0 boys, 4 girls
1 boy, 3 girls
2 boys, 2 girls
3 boys, 1 girl
4 boys, 0 girls
.
The probability that the family has all boys is 1 in 5.
.
HOWEVER, in the real world, the probability is not as straightforward.  But that's a problem for your biology class.