diff --git a/hands_on/numerical_fuzzing/test_var.py b/hands_on/numerical_fuzzing/test_var.py
new file mode 100644
index 0000000..b153ff2
--- /dev/null
+++ b/hands_on/numerical_fuzzing/test_var.py
@@ -0,0 +1,27 @@
+import numpy as np
+import random
+from math import isclose
+
+
+def test_var_deterministic():
+     # Given
+     input = [0, 1, 2, 3]
+     expected = 1.25
+
+     # When
+     result = np.var(input)
+
+     # Then
+     assert isclose(result, expected, abs_tol=0.01)
+
+
+def test_var_fuzzy():
+    # Given
+    expected = 5
+    input = [random.gauss(0, np.sqrt(expected)) for i in range(100000)]
+
+    # When
+    result = np.var(input)
+
+    # Then
+    assert isclose(result, expected, abs_tol=0.05)
diff --git a/hands_on/pyanno_voting/pyanno/tests/test_voting.py b/hands_on/pyanno_voting/pyanno/tests/test_voting.py
index f21a10c..a9fde4d 100644
--- a/hands_on/pyanno_voting/pyanno/tests/test_voting.py
+++ b/hands_on/pyanno_voting/pyanno/tests/test_voting.py
@@ -3,6 +3,8 @@
 from pyanno import voting
 from pyanno.voting import MISSING_VALUE as MV
 
+from math import isclose
+
 
 def test_labels_count():
     annotations = [
@@ -41,3 +43,20 @@ def test_majority_vote_empty_item():
     expected = [1, MV, 2]
     result = voting.majority_vote(annotations)
     assert result == expected
+
+def test_labels_frequency():
+    matrix = [
+        [1, 2, 2, -1],
+        [2, 2, 2, 2],
+        [1, 1, 3, 3],
+        [1, 3, 3, 2],
+        [-1, 2, 3, 1],
+        [-1, -1, -1, 3],
+    ]
+    result = voting.labels_frequency(matrix, 4)
+
+    assert np.all([res != None for res in result])
+    assert len(result) == 4
+    assert np.all(voting.labels_frequency([[-1, -1, -1, -1],[-1, -1, -1, -1]], 4) == np.zeros(4))
+    assert np.all([i >= 0 and i <= 1 for i in result])
+    assert isclose(np.sum(result),1) or isclose(np.sum(result), 0,abs_tol=1e-12)
diff --git a/hands_on/pyanno_voting/pyanno/voting.py b/hands_on/pyanno_voting/pyanno/voting.py
index d5b5747..3694cc7 100644
--- a/hands_on/pyanno_voting/pyanno/voting.py
+++ b/hands_on/pyanno_voting/pyanno/voting.py
@@ -100,3 +100,20 @@ def labels_frequency(annotations, nclasses):
         freq[k] is the frequency of elements of class k in `annotations`, i.e.
         their count over the number of total of observed (non-missing) elements
     """
+    annotations_array = np.ravel(annotations)
+    result = np.zeros(nclasses)
+
+    dim = 0
+    for number in annotations_array:
+        if number != -1:
+            dim = dim + 1
+    if dim !=0:
+        for cl in np.arange(nclasses):
+            aux = 0
+            for anot in annotations_array:
+                if cl == anot:
+                    aux = aux + 1
+            result[cl] = aux / dim
+        return(result)
+    else:
+        return(0)