alleryStart learning →Finding the 90th percentile of a smiling-time distribution means finding the value below which lies:
ATen percent of the area
BHalf of the total area
CAll of the total area
DNinety percent of the area
Answer & Solution
Correct answer: D. Ninety percent of the area
1. A percentile is defined by the area to its left.
2. One worked task is to find the 90th percentile for an eight-week-old baby's smiling time.
3. Probability is represented by area under the curve.
4. The 90th percentile is the value with ninety percent of the probability to its left.
5. So ninety percent of the area lies below that value.
_Source: OpenStax Introductory Statistics 2e (CC BY 4.0), Ch 5 'Continuous Random Variables', sections 5.1-5.3_
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