Retrieve appropriate decile for an income

[Snoopy2003]

Hello,

I have a Deciles & income table:
1 1000$
2 2000$
3 3000$
4 4000$

I have an average income (for example: 3500$).

I wish to get by worksheet functions the appropriate deciles (for example: 3).

How can I do it ?

Thank you