Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Class to 1928 | Class from 1928 | Seats | Quantity | Year(s) of Manufacture | Remarks |
| --- | --- | --- | --- | --- | --- |
| Bi-21 | Bi-21 | 40 | 10.0 | 1921/23 | Trial coaches |
| BCi-21 | BCi-21 | 16/34 | 10.0 | 1921/23 | Trial coaches |
| BDi-21 | BCid-21 | 16/39 | 10.0 | 1923 | Trial coaches |
| Ci-21 | Ci-21 | 58 | 10.0 | 1923 | Trial coaches |
| Di-21b | Cid-21b | 66 | 50.0 | 1922 | Trial coaches |
Question:
What is the average quantity for coaches manufactured in 1921/23, and had 40 seats?
Answer:
10.0