10. antigenic substances on the surface of red blood cells. In a survey of British population the blood group distribution among 1000 people was as follows: 300 had blood group A, 325 had blood group B, 250 had O and 125 AB. Out of this group a person was selected at random, calculate his probability of having blood group AB

Yes, that is correct. Blood group classification is based on the presence or absence of specific antigens on the surface of red blood cells and the corresponding antibodies in the plasma. The four main blood groups are A, B, AB, and O, which are determined by the presence or absence of A and B antigens on the surface of red blood cells and the presence or absence of corresponding antibodies in the plasma. Blood type is an important consideration for blood transfusions and organ transplants, as the presence of certain antigens and antibodies can cause adverse reactions if incompatible blood types are mixed.