Calculating Partial Pressures of Water Vapor (Chem)

[evointrigued]

I have a lab report I'm working on and can't figure out how to answer these questions. I have the answers but I have no idea how to get them (I used an online calculator).

Calculate the partial pressure of water at 21.6 degrees Celsuis. by interpolation from the water vapor pressure table in Appendix 2 of this Lab Manual.

I don't have the lab manual for financial reasons. I had to photocopy the page and didn't realize I needed the part. The lab is due by the time I'll have access to the lab book again.

What does interpolation mean (lexical definition didn't help me) and how does an interpolation calculation in this context look? The chart in my regular text book only has pressures at temperatures that are increments of 1. It includes no decimals. I doubt the lab book has any decimals. I think there's some simple way to calculate but I'm not sure. Does anyone know how?

[mith]

assume a linear relationship between the two closes points to your temp. i.e. figure out a slope intercept line and plug.