Statistics · Superchallenge problem

A frequency table shows how many siblings the students in a class have: $5$ students have $0$ siblings, some students have $1$ sibling, $6$ students have $2$ siblings, and $4$ students have $3$ siblings. The row for $1$ sibling is smudged, but the teacher knows the mean number of siblings is exactly $1.5$. What is the median number of siblings?