If 27 people, working 8 hours a day, can complete a task in 12 days, then in how many days will 18 people finish the task, working 9 hours a day?

16 days

Formula to be used here,

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

where, M = No. of Men, D = No. of Days, h = No. of hours,

⇒ Putting values in the formula,

⇒ 27 x 18 x 12 = 18 x \( { D}_{2 } \) x 9

⇒ \( { D}_{2 } \) = 16 days.