Total doctors in hospital ‘A’ = 200 Male doctors in hospital ‘A’ = 200 × (75/100) = 150 Female doctors in hospital ‘A’ = 200 – 150 = 50 Total doctors in hospital ‘B’ = 200/2 = 100 Male doctors in hospital ‘B’ = 100 × (30/100) = 30 Female doctors in hospital ‘B’ = 100 – 30 = 70 Total doctors in hospital ‘C’ = 150 – 70 = 80 Female doctors in hospital ‘C’ = 30 Male doctors in hospital ‘C’ = 80 – 30 = 50 Female doctors in hospital ‘D’ = 120 Total number of doctors in all hospitals = 120 × (100/20) = 600 Total doctors in hospital ‘D’ = (600 - 200 - 100 - 80) = 220 Total number of male doctors in hospital 'D' = 220 - 120 = 100 Required average = (50 + 70 + 30)/3 = 150/3 = 50