Dsharma put is clearly. The answer is 9, 2, 2 instead of 6, 6, 1. To elaborate further: Check the grammar. The lady answered "the oldest child". Nine (9) is the oldest among 9 , 2, 2. But in a group of children 6, 6, 2, six (6) cannot be referred to as "the oldest". There are 2 kids of age 6. In that case, 6 becomes only "older". Or lese, the mother would have answered "One of the older children is sleeping". GOT it???