Hello coders, today we are going to solve **Day 5: Normal Distribution I HackerRank Solution** which is a Part of **10 Days of Statistics** Series.

**Objective**

In this challenge, we learn about normal distributions.

**Task**

In a certain plant, the time taken to assemble a car is a random variable, ** X**, having a normal distribution with a mean of

**20**hours and a standard deviation of

**2**hours. What is the probability that a car can be assembled at this plant in:

- Less than
**19.5**hours? - Between
**20**and**22**hours?

**Input Format**

There are **3** lines of input (shown below):

```
20 2
19.5
20 22
```

The first line contains **2** space-separated values denoting the respective mean and standard deviation for ** X**. The second line contains the number associated with question

**1**. The third line contains

**2**space-separated values describing the respective lower and upper range boundaries for question

**2**.

If you do not wish to read this information from stdin, you can hard-code it into your program.

**Output Format**

There are two lines of output. Your answers must be rounded to a scale of **3** decimal places (i.e., **1.234** format):

- On the first line, print the answer to question
**1**(i.e., the probability that a car can be assembled in less than**19.5**hours). - On the second line, print the answer to question
**2**(i.e., the probability that a car can be assembled in between**20**to**22**hours).

**Solution – Normal Distribution I **

**C++**

#include <cmath> #include <cstdio> #include <vector> #include <iostream> #include <algorithm> using namespace std; double normal_dist(double m, double sd, double x) { double p = 0.5*(1 + erf((x-m)/(sd*sqrt(2.0)))); return p; } int main() { /* Enter your code here. Read input from STDIN. Print output to STDOUT */ double m = 20, sd = 2, x = 19.5, a = 20, b = 22; double p1 = normal_dist(m, sd, x); double p2 = normal_dist(m, sd, b) - normal_dist(m, sd, a); printf("%0.3f\n%0.3f", p1, p2); return 0; }

**Disclaimer:** The above Problem **(Normal Distribution I)** is generated by **Hacker Rank **but the Solution is Provided by **CodingBroz**. This tutorial is only for** Educational** and **Learning** Purpose.