Learn keras API basics through solving simple numerical data analysis question.

An experimental Covid-19 vaccine was tested on patients ranging from age 13~103 in a clinical trial. The trial had 21000 participants. Half of the participants were under 65 years old, and the other half was 65 years of age or older. The trial showed that around 95% of patients 65 or older experienced side effects from the drug, and around 95% of patients under 65 experienced no side effects.

1. Data preprocessing, creating dummy data from out system model (which is a made-up story in this case)
2. Creating a simple Neural Network by using Keras API
3. Training, first complie the model by using compile() , then train the model by using fit()
4. Testing, the model make predictions for the test_samples based on what it learned from the train_samples, this process is called "inference"
5. Plotting a confusion Matrix to evaluate how well the model perform
6. Save and Load the model, there are three different ways to save a Keras model with its weights both and separately