How many cubic meters of earth must be dug out to make a well 28 m deep and 2.8 m in diameter ? Also , find the cost of plastering its inner surface ata Rs 4.50 per sq.meter.
`"Radius of the well"=2.8/2=1.4 m`
`"Depth of the well"=28m`
`"Therefore, volume of earth dug out "= pir^h`
`"Area of curved surface"=2pirh`
Cost of plastering the rate of Rs 4.50 per sq m
`= Rs. 246.40xx450`
`= Rs 1108.80`