probe pool calculation help

Here are 2 questions:

 

1. You have a probe pool at 1000 probes in a single pool. The pool concentration is 20nM. We use 5ul of this into our ligation reaction. What is the concentration of each probe in each reaction in fmol/probe?  I calculated this out as 100fmol/reaction (20nM*5ul), then 0.1 fmol/probes (100fmol/1000probes). 

 

2. You order some new probes to spike into the 20nM pool. You order as 10 probes in lyophiized (dried) form. You can resuspend dried tube how we want, then spike in some volume of it into the original 20nM probe pool. You want the final molarity to stay as above, 0.1fmol/probe. Calculate and make sure each probe (old and new) are at the same molarity in the end. 

I am stuck on this one, help!