Question

5 men working 6 hours a day can dig a trench 180m long in 4 days. How many days would 8 men working 3 hrs a day take to dig a trench 220m long​

Answer 1

assuming efficiency of each man to dig trench, in one day, for one hour is constant,

$e=\frac{180}{4\times6\times5}=\frac{3}{2}$

so one man, working for one hour in one day can dig 1.5 m

so 8 men, working 3 hours a day and will take, say $d$ number of days and efficiency will be constant. so,

$\frac32=\frac{220}{8\times3\times d}$

$\implies d=\frac{55}9=6.12$