I believe if I did this correctly, it should be 4 2/7, hope this helps!
Yes because they are all boys and they are all in the same year
On average, 2 will fall apart. We can tell this by making a proportion.
1/20 = x/40 ---> cross multiply
1*40 = 20*x ---> multiply
40 = 20x ----> divide by 20
2 = x
