The period in question is 4 years so multiply by 4 (although not all litigants were present during all 4 years so you can back it off a little).
And 5k is too low. Google gave a 10% raise across the board around the time this information came out. So assume 150k salary * 10% = 15k. Salaries also continued to rise more rapidly after the 10% raise, but it's hard to say by how much without having access to the internal data.
I'm not being snarky; where does 4 years come from? Do we have start/end dates on when the agreement was formed/ended? If we do, then I'm totally willing to revise my judgement on this. Also, 10% from Google does not translate to 10% across the board, only to any employees who would be hired by Google, which would surely not be 100%.
From the linked wikipedia article: "The civil class action which was filed by five plaintiffs, one of whom has died, accused the tech companies of collusion to not recruit one another's employees between 2005 and 2009."
Hence 4 years of wage suppression. Given tech salaries in SV, $5k is off by about an order of magnitude -- especially when you consider the knock-on effects of job mobility that was systemically quashed by collusion (i.e. moving jobs => better pay => faster career progression => compounded earnings).
Your first question is answered by beambot. The 10% argument is that Google felt it had to raise salaries by that much for everyone after collusion ended, in order to retain employees.
And 5k is too low. Google gave a 10% raise across the board around the time this information came out. So assume 150k salary * 10% = 15k. Salaries also continued to rise more rapidly after the 10% raise, but it's hard to say by how much without having access to the internal data.