diff --git a/build.py b/build.py
index c7d540b..38327fa 100644
--- a/build.py
+++ b/build.py
@@ -1,22 +1,24 @@
-def get_categorical_variables(df):
-    return []
+import pandas as pd
+df = pd.read_csv('data/employee_retention_data.csv')
 
+def get_categorical_variables(df):
+    return df.select_dtypes(include=['object']).columns
 
 def get_numerical_variables(df):
-    return []
+    return df.select_dtypes(exclude=['object']).columns
 
 
 def get_numerical_variables_percentile(df):
-    pass
+    return df.select_dtypes(exclude=['object']).describe()
 
 
 def get_categorical_variables_modes(df):
-    pass
+    return df.select_dtypes(include=['object']).mode()
 
 
 def get_missing_values_count(df):
-    pass
+    return df.isnull()
 
 
 def plot_histogram_with_numerical_values(df):
-    pass
+    return df.plot.hist(bins=20)
diff --git a/build.pyc b/build.pyc
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index 0000000..e49c421
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diff --git a/tests/__init__.pyc b/tests/__init__.pyc
new file mode 100644
index 0000000..62dec64
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diff --git a/tests/test_get_categorical_variables.pyc b/tests/test_get_categorical_variables.pyc
new file mode 100644
index 0000000..7fbda9d
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