The samples he chose may not be a representative sample because the number of students per foreign language class may not be the same. One class may have a very large number of students while another may have only a few. Taking equal number of students per class is not a representative sample.<span />
Answer:
2
b
+
9
m
+
6
x
+
10
Step-by-step explanation:
2
b
+
4
+
6
x
+
6
+9
m
2
b
+
6
x
+
10
+
9m
2
b
+
6
x
+
9
m
+
10
= 2
b
+
9
m
+
6
x
+
10
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Since D=MV, we can infer that M=D/V
That is your equation----------------^