4 A well is dug whose diameter is 4 m and the depth is 10 m. Find the quan
of earth taken out. Calculate the cost of plastering the curved immer sur
*5.00 per sq. m.
Answers
Step-by-step explanation:
radius = 2 m
height = 10 m
volume of earth taken out = volume of cylinder
= 2πrh
= 2×22×2×10/7
= 880/7
=125.7 ( approx)
Answer:
Diameter of well = 4m
Depth of well = 10m
Volume of cylindrical well = πr²h m³
= (3.14 x 2 x 2 x 10) m³
= 125.6 m³
Hence 125.6 cm³ of earth is taken out.
Inner CSA of well = 2πrh m²
= (2 x 3.14 x 2 x 10) m²
= 125.6 m²
cost of plastering = Rs. (5 x 125.6)
= Rs. 628
CASE 2 --
In case if the base is also to plastered then,
CSA of well + Base area are to be added,
Base area = (3.14 x 2 x 2) m²
= 12.56 m²
Total area to be plastered = (125.6 + 12.56) m²
= 138.16 m²
Total cost of plastering = Rs. (138.16 x 5)
= Rs. 690.8 = Rs. 691 (approx.)
Hence Rs. 691 are needed to plaster it.