## Can you predict the strength of concrete?

### 📖 Background

You work in the civil engineering department of a major university. You are part of a project testing the strength of concrete samples.

Concrete is the most widely used building material in the world. It is a mix of cement and water with gravel and sand. It can also include other materials like fly ash, blast furnace slag, and additives.

The compressive strength of concrete is a function of components and age, so your team is testing different combinations of ingredients at different time intervals.

The project leader asked you to find a simple way to estimate strength so that students can predict how a particular sample is expected to perform.

### 💾 The data

The team has already tested more than a thousand samples (source):

##### Compressive strength data:

- "cement" - Portland cement in kg/m3
- "slag" - Blast furnace slag in kg/m3
- "fly_ash" - Fly ash in kg/m3
- "water" - Water in liters/m3
- "superplasticizer" - Superplasticizer additive in kg/m3
- "coarse_aggregate" - Coarse aggregate (gravel) in kg/m3
- "fine_aggregate" - Fine aggregate (sand) in kg/m3
- "age" - Age of the sample in days
- "strength" - Concrete compressive strength in megapascals (MPa)

* Acknowledgments: I-Cheng Yeh, "Modeling of strength of high-performance concrete using artificial neural networks," Cement and Concrete Research, Vol. 28, No. 12, pp. 1797-1808 (1998)*.

```
suppressPackageStartupMessages(library(tidyverse))
df <- readr::read_csv('data/concrete_data.csv', show_col_types = FALSE)
head(df)
```

### 💪 Challenge

Provide your project leader with a formula that estimates the compressive strength. Include:

- The average strength of the concrete samples at 1, 7, 14, and 28 days of age.
- The coefficients
, ... , to use in the following formula:

### 🧑⚖️ Judging criteria

This is a community-based competition. The top 5 most upvoted entries will win.

The winners will receive DataCamp merchandise.

### ✅ Checklist before publishing

- Rename your workspace to make it descriptive of your work. N.B. you should leave the notebook name as notebook.ipynb.
**Remove redundant cells**like the judging criteria, so the workbook is focused on your work.- Check that all the cells run without error.

### ⌛️ Time is ticking. Good luck!