Eight persons can finish a work in 20 days. After 5 days they were requested to complete the work in the next 8 days. How many more persons should join the group to fulfil the requirement?

7

Formula to be used here,

\( { M}_{1 } \) x \( { D}_{1 } \)  = \( { M}_{2 } \) x \( { D}_{2 } \)

where, M = No. of men, D = No. of Days,

⇒ Putting in the values,

⇒ 8 x 15 = \( { M}_{2 } \) x 8 

⇒ \( { M}_{2 } \) = 15 - 8 = 7 men.