https://www.gregmat.com/problems/quant?problem=a-researcher-collected-data-on-the-number
A researcher collected data on the number of children in 30 separate families. Unfortunately, the data for two of the families is not legible, but the researcher does recall that the mean number of children for all 30 families is 2.9 and that no family had 0 or greater than 5 children. How many distinct arrangements are possible regarding the missing data for the number of children of the two families? answer should be 6, not 5