Library

They packed books in the library. They used 45 cm of wrapping paper per book. Wrapping papers are sold in rolls of 3 meters. How many such roles do they need to wrap 20 books?

Correct answer:

n =  3

Step-by-step explanation:

$$\begin{gathered} a=45\text{cm}\to \text{m}=45:100\text{m}=0.45\text{m} \\ b=3\text{m} \\ {n}_0=\frac{20\cdot a}{b}=\frac{20\cdot \frac{9}{20}}{3}=3 \\ n=\lceil n_0\rceil =\lceil 3\rceil =3 \end{gathered}$$

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