RESUMEN
In addition to the A-and K-type questions, the X<SUB>2</SUB> type question has been introduced into, and the K'-type question has been eliminated from the Japanese Medical Licensure Examination since 1997. The expected correct answer ratio (ECAR) without any knowledge is 10% for the X<SUB>2</SUB>-type in contrast to 20% for the K2-type. However it still becomes 100% with an 80% knowledge. We designed a formula to study the relation between the knowledge quantity (KQ) and ECAR. The ECAR is 7%, 13%, 25%, 43%, 70%, and 100% for the X<SUB>1, 2</SUB>-type in which the number of answer (NA) is indicated as one or two, while it is 5%, 10%, 20%, 40%, 70%, and 100% for the X<SUB>2, 3</SUB>-type in which NA is indicated as two or three. The KQ difference between 80% and 100% can be reflected to ECAR in these types and considered to be the better question type.