Answer: 40
Step-by-step explanation:
Given
Radius of disc [tex]r=4\ cm[/tex]
The dimension of the sheet is [tex]84\times 24\ cm^2[/tex]
Area of a single disc
[tex]\Rightarrow a=\pi r^2=\frac{22}{7}\times 4^2\\\\\Rightarrow a=\frac{352}{7}\ cm^2[/tex]
Area of sheet
[tex]\Rightarrow A=84\times 24=2016\ cm^2[/tex]
No. of discs that can be cut off the sheet are
[tex]\Rightarrow n=\dfrac{A}{a}=\dfrac{2016}{\frac{352}{7}}=\dfrac{2016\times7}{352}\\\Rightarrow n\approx 40[/tex]
The total area of the disc is
[tex]\Rightarrow na=40\times\frac{352}{7}=2011.428\ cm^2[/tex]
Sheet wasted
[tex]\Rightarrow A-na=2016-2011.428=4.57\ cm^2[/tex]
