80% of what is 56
0.80x = 56
x = 56/0.80
x = 70
check..
80% of 70 is 56
.80(70) = 56
56 = 56 (correct)
so there were 70 items on the test
B. Dependent it isn’t clear of why the apple was thrown across the room
Answer:
![33\%](https://tex.z-dn.net/?f=33%5C%25)
Step-by-step explanation:
To work out the percentage of the circle shaded blue, we first must work out the area of the whole circle.
Area of the whole circle = ![\pi r^2](https://tex.z-dn.net/?f=%5Cpi%20r%5E2)
![r=4+3+3\\\pi * (4+3+3)^2=\pi*10^2=100\pi](https://tex.z-dn.net/?f=r%3D4%2B3%2B3%5C%5C%5Cpi%20%2A%20%284%2B3%2B3%29%5E2%3D%5Cpi%2A10%5E2%3D100%5Cpi)
Now we need to work out the area of the blue 2d torus, by finding out the area of the blue circle, then subtracting the area of the innermost white circle.
Blue shaded area = ![\pi(r_{0}{^2}-r_{1}{^2})](https://tex.z-dn.net/?f=%5Cpi%28r_%7B0%7D%7B%5E2%7D-r_%7B1%7D%7B%5E2%7D%29)
![r_0=4+3\\r_1 = 4\\\pi ((4+3)^2-(4)^2)= \pi (7^2-4^2)=33 \pi](https://tex.z-dn.net/?f=r_0%3D4%2B3%5C%5Cr_1%20%3D%204%5C%5C%5Cpi%20%28%284%2B3%29%5E2-%284%29%5E2%29%3D%20%5Cpi%20%287%5E2-4%5E2%29%3D33%20%5Cpi)
Now we have the total areas of each, we can work out the fraction of blue to non blue by dividing the blue area by the total area, and then working out the percentage by multiplying by 100.
![\frac{33\pi}{100\pi}*100=\frac{33\pi}{\pi}=33\%](https://tex.z-dn.net/?f=%5Cfrac%7B33%5Cpi%7D%7B100%5Cpi%7D%2A100%3D%5Cfrac%7B33%5Cpi%7D%7B%5Cpi%7D%3D33%5C%25)
Area Of Circle:
=3.14 • (2.5)^2
=3.14 • 6.25
=19.625cm or 19.63