Can some help me!!

Situation:

OVERCOME Cystic Fibrosis
Cystic fibrosis in France

→2 million people are unknowingly carriers healthy from the cystic fibrosis gene.

→130 children are bom each year with cystic fibrosis.

→1 in 4,300 newborns is affected by the disease.

→Nearly 7,000 people have cystic fibrosis


A couple would like to have a third child. They already have an unaffected boy and a girl with cystic fibrosis,
They consult a geneticist doctor to find out what is the risk of transmitting this hereditary disease again.

Explain to this couple what is the probability of having a second sick child.​