Hello coders, today we are going to solve **Day 8: Pearson Correlation Coefficient HackerRank Solution** which is a Part of **10 Days of Statistics** Series.

**Task**

The regression line of ** y** on

**is**

*x***3**, and the regression line of

*x*+ 4*y*+ 8 = 0**on**

*x***is**

*y***4**. What is the value of the Pearson correlation coefficient?

*x*+ 3*y*+ 7 = 0**Solution – Day 8: Pearson Correlation Coefficient**

```
# Step 1, Rewrite the 2 lines in proper form
Rewrite the 2 lines as:
y = -2 + (-3/4) * x
x = -7/4 + (-3/4) * y
so b1 = -3/4 and b2 = -3/4
# Step 2, Apply Pearson's Coefficient formula
Let p = pearson coefficient
Let x_std = standard deviation of x
Let y_std = standard deviation of y
From the tutorial we have:
p = b1 (x_std / y_std)
p = b2 (y_std / x_std)
Multiplying these 2 equations together we get
p^2 = b1 * b2
p^2 = (-3/4) * (-3/4)
p^2 = 9/16
p = 3/4 or -3/4 (depending on correlation of x and y)
# Step 3, Find out if p is postive or negative
Notice that both of the original line equations have negative slopes, so x and y are negatively correlated by definition.
So, p = -3/4
```

The **Correct** answer is **-3/4**.

**Disclaimer:** The above Problem **(Day 8: Pearson Correlation Coefficient)** is generated by **Hacker Rank** but the Solution is Provided by** CodingBroz**. This tutorial is only for **Educational** and **Learning** Purpose.