Question Number 102857 by mathocean1 last updated on 11/Jul/20
Commented by PRITHWISH SEN 2 last updated on 11/Jul/20
$$\frac{\mathrm{11}}{\mathrm{2}}\left\{\mathrm{2a}+\left(\mathrm{11}−\mathrm{1}\right)\mathrm{4}\right\}=\mathrm{374} \\ $$$$\mathrm{a}=\mathrm{14} \\ $$$$\therefore\:\:\mathrm{It}\:\mathrm{takes}\:\mathrm{14}\:\mathrm{mins}.\:\mathrm{to}\:\mathrm{sweep}\:\mathrm{the}\:\mathrm{first}\:\mathrm{class}\:\: \\ $$