Generate random # of days based on other criteria

Customer has 30 deposits in July, so C2=30
We want to look at 50% of deposits, so C4=(C2*.50)=15

What I want is for Excel to tell the auditor which business days of deposits they should view to make the sample truly random, i.e. excel would pick 15 business days in August in cells C6 & down.

Can it be done formulatically (is that a word?)....have never gotten the hang of macros..

Thanks,
Jeff

sorry, you lost me. I have attached a sample sheet, where the test results are under "Review Dates"