Question Number 69347 by Askash last updated on 22/Sep/19
$${If}\:{a}\:{well}\:{is}\:{dug}\:\mathrm{21}{m}\:{deep}\:{and}\:\mathrm{1}.\mathrm{4}{m} \\ $$$${in}\:{radius},\:{how}\:{much}\:{earth}\:{is}\:{dug} \\ $$$${out}\:{from}\:{it}?\:{If}\:{the}\:{inner}\:{wall}\:{of} \\ $$$${well}\:{is}\:{plastered}\:{at}\:\:{Rupees}\:\mathrm{20}\: \\ $$$${per}\:{m}^{\mathrm{2}} .\:{WHAT}\:\:\mathbb{WILL}\:\:{BE}\:\:{ITS} \\ $$$$\mathcal{COST}\:? \\ $$$$ \\ $$$$ \\ $$$$ \\ $$$$ \\ $$$$ \\ $$$$ \\ $$$$ \\ $$$$ \\ $$$$ \\ $$$$ \\ $$
Answered by MJS last updated on 22/Sep/19
$$\mathrm{it}'\mathrm{s}\:\mathrm{simply}\:\mathrm{a}\:\mathrm{cylinder} \\ $$$$\mathrm{the}\:\mathrm{volume}\:\mathrm{is}\:{r}^{\mathrm{2}} \pi{h} \\ $$$$\mathrm{the}\:\mathrm{lateral}\:\mathrm{surface}\:\mathrm{is}\:\mathrm{2}{r}\pi{h} \\ $$