Percentiles Statistics Example 4
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Example 4
mediumA baby's weight is at the 25th percentile for her age group. Her parents are worried she is underweight. Is their concern justified? Explain what the 25th percentile means in this context.
Solution
- 1 Step 1: The 25th percentile means 25% of babies her age weigh less and 75% weigh more. This is the same as .
- 2 Step 2: The 25th percentile is within the normal range — it does not indicate a health problem. Doctors typically become concerned below the 5th percentile. Being at the 25th percentile simply means the baby is lighter than average but still within healthy bounds.
Answer
The concern is not necessarily justified. The 25th percentile is within the normal range — 1 in 4 healthy babies will be at or below this level. Medical concern typically arises below the 5th percentile.
Percentiles in medical contexts (growth charts) describe relative position, not health status. The 25th percentile means the child is lighter than the average but is not unusual. Doctors use very low or very high percentiles (below 5th or above 95th) as flags for potential issues.
About Percentiles
Percentiles are values that divide a ranked distribution into 100 equal parts. The th percentile is the value below which of the data falls, telling you where a specific observation stands relative to the entire dataset.
Learn more about Percentiles →More Percentiles Examples
Example 1 easy
A student scored in the 85th percentile on a standardised test with 200 test-takers. What does this
Example 2 mediumGiven the sorted data set of 20 values: 12, 15, 18, 20, 22, 25, 27, 30, 32, 35, 38, 40, 42, 45, 48,
Example 3 mediumIn a class of 40 students, a student scored higher than 32 others. What percentile is the student at
Example 5 hardIn a normally distributed data set with mean 500 and standard deviation 100, approximately what valu