Question

use the accompanying radiation levels (in $\frac{w}{kg}$) for 50 different cell - phones. find the percentile $p_{25}$. $p_{25}=square\frac{w}{kg}$ (type an integer or a decimal. do not round.) 0.21 0.27 0.28 0.43 0.57 0.60 0.61 0.66 0.72 0.83 0.87 0.87 0.89 0.90 0.97 0.98 1.01 1.04 1.04 1.09 1.10 1.11 1.11 1.12 1.14 1.14 1.15 1.15 1.16 1.18 1.22 1.23 1.26 1.27 1.27 1.31 1.32 1.33 1.34 1.35 1.35 1.36 1.39 1.41 1.43 1.46 1.51 1.51 1.53 1.55

Explanation:

Step1: Calculate the index

The formula to find the index $i$ for the $p$ - th percentile is $i=\frac{p}{100}\times n$, where $p = 25$ and $n = 50$. So $i=\frac{25}{100}\times50=12.5$.

Step2: Determine the percentile value

Since the index $i = 12.5$ is not an integer, we round up to the next - integer. The 13th value in the ordered data set is the 25 - th percentile. Arranging the data in ascending order (it seems to be already in ascending order as given), and counting from the first value, the 13th value is $0.89$.

Answer:

$0.89$