Question

a well is dug whose daimeter is 4 and the depth is10 m find the quantity of earth taken out .calculate the cost of plastering the curved (inner) surface at ₹ 5.00 per sq m

Answer 1

HERE'S YOUR ANSWER


Diameter of the well = 4m
So, Radius of the well = 4/2 = 2m

Now, Depth of the well = Height of the well = 10m

Now, Volume of the earth taken out = $\pi r^2 h$
                                                         = $(3.14) * 2^{2} * 10$
                                                         = 3.14*40 = 125.6$m^{3}$

Also, Curved surface area of the well will be = $2\pi rh$
                                                                       = 2*3.14*2*10
                                                                       = 125.6$m^{2}$

Now, Cost of plastering the inner surface at a rate of Rs.5 per $m^{3}$
                                                                       = 125.6*5 = Rs. 628
 

HOPE HELPED !!

Answer 2

Well hv a shpe of Cylinder...so v take here the formulae of vol. of cylinder...

d=4m,
r=d/2=4/2=2m,

nd h=10m

vol. of Cylinder =
$\pi \: r ^{2} h$
==3.14×2×2×10
=125.6 m^3--Ans

The vol of the soil that is taken out is 125.6 m^3

nw v find the inner surfce ar of cylinder or well to plastering

curved or inner surface area of cylinder =


==2×3.14×2×10

=125.6m^2

so rate is ₹5

nw

125.6×5

=₹628__ans