Let the dominant allele be 'A' and let the recessive allele be 'a'. (a) Member 4 could be Aa (carrier) or aa (unaffected).  Member 5 is aa (affected).  Member 6 could be Aa (carrier) or aa (unaffected).  (b) Member 14 is a carrier female which means the genotype is Aa. Member 15 is an unaffected male (AA). So, the probability that the first child is a haemophilic male is 1/4.