# Percentile no. $$$25$$$ of $$$1$$$, $$$-5$$$, $$$2$$$, $$$4$$$, $$$-3$$$, $$$6$$$, $$$7$$$, $$$0$$$, $$$2$$$, $$$5$$$, $$$-4$$$, $$$7$$$

Related calculators: Five Number Summary Calculator, Box and Whisker Plot Calculator

### Your Input

**Find the percentile no. $$$25$$$ of $$$1$$$, $$$-5$$$, $$$2$$$, $$$4$$$, $$$-3$$$, $$$6$$$, $$$7$$$, $$$0$$$, $$$2$$$, $$$5$$$, $$$-4$$$, $$$7$$$.**

### Solution

The percentile no. $$$p$$$ is a value such that at least $$$p$$$ percent of the observations is less than or equal to this value and at least $$$100 - p$$$ percent of the observations is greater than or equal to this value.

The first step is to sort the values.

The sorted values are $$$-5$$$, $$$-4$$$, $$$-3$$$, $$$0$$$, $$$1$$$, $$$2$$$, $$$2$$$, $$$4$$$, $$$5$$$, $$$6$$$, $$$7$$$, $$$7$$$.

Since there are $$$12$$$ values, then $$$n = 12$$$.

Now, calculate the index: $$$i = \frac{p}{100} n = \frac{25}{100} \cdot 12 = 3$$$.

Since the index $$$i$$$ is an integer, the percentile no. $$$25$$$ is the average of the values at the positions $$$i$$$ and $$$i + 1$$$.

The value at the position $$$i = 3$$$ is $$$-3$$$; the value at the position $$$i + 1 = 4$$$ is $$$0$$$.

Their average is the percentile: $$$\frac{-3 + 0}{2} = - \frac{3}{2}$$$.

### Answer

**The percentile no. $$$25$$$A is $$$- \frac{3}{2} = -1.5$$$A.**