CFA Mock PM, Question #20

This is a very simple question, but the answer doesn’t look right to me.

The answer is B, 21, which is the 8th number in the sample.

I chose C, 24.2, I used the formula in the book. (n+1)*y. so 11*80% = 8.8, and interoplation between 21 and 25.

which one is right?

someone else asked this qn today. i think it’s an error. it should be C i think

Also…i don’t get it. if you put all the numbers in excel and let it calculate 80th percentile, it gives 21.8.

that’s strange. the alternative explanation is this: 80th percentile means 80% of the numbers are at or below 21. i still think it should be C tho