UPSC 2014 CDS II Math Paper

Number of days taken by 10 persons to dig 8 feet trench = 12 days
∴ Number of days taken by 1 person to dig 1 feet trench=

12×10

8

=15days
Number of days taken by 8 persons to dig 1 feet trench =

15

8

days
∴ Number of days taken by 8 persons to dig 6 feet trench =

15

8

×6=11.25days
Alternative Method:
Suppose 8 persons will take x days.
⇒8×8×x=10×6×12
⇒x=11.25 days