Normalize a column

[#1]

TLDR: How do I normalize a column to itself?

See attached. I have:

• Column A = 0,1,2,3. Maybe think of this as like an ID number
• Column B. Think of this as a timestamp
• Column C. This is the data

Now I want column D to have the data in Column C, ONLY when B=1.

As you can see in the attached file, I have manually copy-pasted the yellow cells from C into D. Pasted over and over.

Therefore when I do D/C, I'm basically normalizing the whole of column C, to these special yellow values. This is the reason I'm doing all this, is to find D/C. So a value of 0.9 in this column means C is lower than the yellow C's, and 1.1 means it's higher than the yellow C's. 

So, long story short, what is the formula that goes in D, to be able to get the yellow values?

[#2]

Hogi, This is the solution! Thanks! A little weird that I have to use a "median" function since there is no median in sight, but I see what it's doing. Thanks! I'll also check out the Marketplace Addin

[#3]

Thanks! This does work, but is a bit unweildy for a human to view when I have a large dataset. Hogi's answer is simpler but thanks for the tip anyway!