The following ten observations are a sample drawn from a normal population: 25,20,18, -5,35, 21, -11,8,20, and 9. The fourth quintile (80th percentile) of the sample is closest to:
Ranking the sample from smallest to largest, we have -11, -5,8,9,18,20,20,21,25, and 35. The fourth quintile (80th percentile) is the eighth largest of these ordered numbers. The eighth largest number is 21.