Classroom 64434

In physics class, students estimated the volume of the trash can in the classroom. There is a record of the answers of 20 pupils on the board. The actual volume of this dustbin was 12 liters. By how many liters does the average student estimate differ from this value?

Volume:	Number of pupils:
5L	3
6l	3
8l	6
9L	1
10L	6
15L	1

Correct answer:

x =  3.75 l

Step-by-step explanation:

$$\begin{gathered} a=\frac{5\cdot 3+6\cdot 3+8\cdot 6+9\cdot 1+10\cdot 6+15\cdot 1}{20}=\frac{33}{4}=8.25\text{l} \\ b=12\text{l} \\ x=b-a=12-\frac{33}{4}=\frac{12\cdot 4}{4}-\frac{33}{4}=\frac{48}{4}-\frac{33}{4}=\frac{48-33}{4}=\frac{15}{4}=\frac{15}{4}\text{l}=3.75\text{l} \end{gathered}$$

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