It sure had me occupied for a while there.
The very first thought that popped up in my head when I saw this: How in the world can you be 30% one race and 70% another? How?!? If your lola is, say, Chinese, and everyone else is Pinoy, you'd be 25% Chinese. If it's your great grand lola, 12.5%. If it's two of your great grand lolas, then it's back to 25%. It may have kinda driven me nuts, as my math skills are quite rusty, so I had no choice but to take my problem to Twitter.
Thankfully, I'm from Pisay. And that means I have smart high school batchmates haha :p. I had an answer within minutes, thanks to math genius Chris (who blogs here). If we were to assume that the Bayo people rounded off, then it would take a minimum of five generations. But wait, there's more! There's an illustration! XD
Ah, finally, peace of mind.
Now let's do 80% - 20%? :p