A9. Jožko is planning to tile a courtyard that is $5.5 \mathrm{~m}$ long and $4.5 \mathrm{~m}$ wide. On the floor, he will lay tiles of size $20 \mathrm{~cm} \times 20 \mathrm{~cm}$, which are packed in boxes of 20 tiles each. What is the minimum number of boxes of tiles he will need?
(A) 30
(B) 31
(C) 32
(D) 62
(E) 619
A9. The courtyard that Jožko will pave has an area of $5.5 \cdot 4.5=24.75 \mathrm{~m}^{2}$. Each tile has an area of $0.2^{2}=0.04 \mathrm{~m}^{2}$. One box of tiles will cover $0.8 \mathrm{~m}^{2}$ of the ground. For paving the entire ground, he will need $24.75: 0.8=30.9375$ or at least 31 boxes of tiles.