Question

for any set of data, what must be done to the data before percentiles can be determined?

choose the correct answer below.

a. the quartiles of the data set must be found.
b. the frequency of each piece of data must be found.
c. the data must be summed.
d. the data must be ranked.

Explanation:

Define percentiles and their requirements

Percentiles divide a set of data into 100 equal parts. To determine any percentile, we must know the relative standing of each data value.

Analyze the necessity of ordering data

Using the Quartiles knowledge point

$$ \text{Data must be arranged in ascending order (ranked) before finding position-based measures.} $$

Evaluate the given options

• Option A: Finding quartiles is not a prerequisite; quartiles themselves are specific percentiles (25th, 50th, 75th).
• Option B: Finding individual frequencies is not required to determine percentiles.
• Option C: Summing the data is used for calculating the mean, not percentiles.
• Option D: Ranking (sorting) the data from smallest to largest is the essential first step.

Answer:

• (A) The quartiles of the data set must be found.
• (B) The frequency of each piece of data must be found.
• (C) The data must be summed.
• (D) The data must be ranked. (Correct answer)