- Prepare
- Tutorials
- 10 Days of Statistics
- Day 1: Standard Deviation

# Day 1: Standard Deviation

# Day 1: Standard Deviation

**Objective**

In this challenge, we practice calculating *standard deviation*. Check out the *Tutorial* tab for learning materials and an instructional video!

**Task**

Given an array, , of integers, calculate and print the standard deviation. Your answer should be in decimal form, rounded to a scale of decimal place (i.e., format). An error margin of will be tolerated for the standard deviation.

**Example**

The sum of the array values is and there are elements. The mean is .

Subtract the mean from each element, square each result, and take their sum.

Their sum is 18. Take the square root of to get , the standard deviation.

**Function Description**

Complete the *stdDev* function in the editor below.

*stdDev* has the following parameters:

- *int arr[n]:* an array of integers

**Prints**

- *float:* the standard deviation to 1 place after the decimal

**Input Format**

The first line contains an integer, , denoting the size of arr.

The second line contains space-separated integers that describe .

**Constraints**

**Output Format**

Print the *standard deviation* on a new line, rounded to a scale of decimal place (i.e., format).

**Sample Input**

STDIN Function ----- -------- 5 arr[] size n = 5 10 40 30 50 20 arr =[10, 40, 30, 50, 20]

**Sample Output**

```
14.1
```

**Explanation**

First, find the *mean*:

Next, calculate the squared distance from the mean, , for each :

Now compute , so: