Question

A path 2m wide surrounds a circular pond of diameter 40m how many cubic meters of gravel are required to grave the paTh to a depth of 20cm ?

Answer 1

area of the path = π (40/2 + 2 )² - π (40/2)² = 84 π m²
amount of gravel needed =  area * depth = 84 π m² * 0.20 m 
    = 16.8 π m³

Answer 2

Answer:

$Now,\\Volume \: (V)=52.8\:m^{3}$

Step-by-step explanation:

$Dimensions \: of \: the \: circular \: pond :$

$width \: of \: the \: path (w)=2\:m$

$Diameter (d)=40\:m \\Radius (r) = \frac{d}{2}\\=20\:m$

$depth (h) = 20\:cm \\=\frac{20}{100}\:m \\=\frac{1}{5}\:m$

$Radius \: of \: outer \: circle (R) = r+w = 20+2 = 22\: m$

$Now,\\Volume \: (V)= \pi (R+r)(R-r)\times h\\=\frac{22}{7} \times (22+20)(22-2)\times \frac{1}{5}\\=\frac{22}{7}\times 42 \times 2\times \frac{1}{5}\\=\frac{1848}{35}\\=52.8 m^{3}$

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