Mass of 1 sheet = (160 g/m^2)*(1/8 m^2) = 160/8 g = 20 g
mass of 25 sheets = (25 sheets)*(20 g/sheet) = 25*20 g = 500 g
The second choice is the answer
Can you post it again it is black
For perimeter you add up the two sides so 15 + 21 equals 36
the surface area of the sphere is π/4 cm^3
<h3>How to determine the surface area</h3>
It is important to know the formula for surface area and volume of a sphere
Surface area = 
Volume = 
First, let's determine the value of radius, r
The value for volume was given as 256/3π cm3.

Pi cancels out and we have cross multiply to get the radius


Make r the subject of the formula
![r = \sqrt[3]{\frac{768}{12} }](https://tex.z-dn.net/?f=r%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B768%7D%7B12%7D%20%7D)
![r = \sqrt[3]{64}](https://tex.z-dn.net/?f=r%20%3D%20%5Csqrt%5B3%5D%7B64%7D)
r = 4
Let's substitute to find the surface area
Surface area = 
Surface area = π/4
Surface area = π/4 cm^3
Thus, the surface area of the sphere is π/4 cm^3
Learn more about a sphere here:
brainly.com/question/10171109
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