Flowerbeds

There are three square flower beds on the square grassy plot. What percentage is the grassed part of the land when one side is 35 m, and the side of the flowerbed is 10 m?

Correct answer:

p =  75.5 %

Step-by-step explanation:

$$\begin{gathered} a=35\text{m} \\ b=10\text{m} \\ n=3 \\ {S}_1=b^2=10^2=100{\text{m}}^2 \\ {S}_2=a^2=35^2=1225{\text{m}}^2 \\ p=100\cdot \frac{S_2-n\cdot S_1}{S_2}=100\cdot \frac{1225-3\cdot 100}{1225}=\frac{3700}{49}\%=75.5\% \end{gathered}$$

Try another example