Step-by-step explanation:
The gender of a child which is either a boy or a girl is determined by the XX-chromosomes, or XY-chromosomes.
Since the couple plan to have 5 children, the chance of a child being a boy is equal to the chance of it being a girl - the chances are 50/50.
What we do to achieve our aim is to run a simulation that would add an X or Y to an X for all 5 children.
Doing this 125 times, we obtain the number of trials we desire.
For each trial, we get for each child, C:
C1: X + (X or Y)
C2: X + (X or Y)
C3: X + (X or Y)
C4: X + (X or Y)
C5: X + (X or Y)
Since the chance of having an X is equal to the chance of having a Y, they equal probability, which is 0.5 for each.
The answer is 8.33333333333333333...
30(-2/5)²(5/8) = 30*(4/25)*(5/8) = 30*4/(5*8) = 3
