Formula M1×D1×H1∕W1=M2×D2×H2∕W2 Where, M= Number of men, D= Number of days, H= Number of hours, W= Work doneLet, y additional workers are required; M1=480,D1=10,H1=10,W1=
1
4
M2=(480+y),D2=20,H2=8,W2=(1−
1
4
)=
3
4
Using the above formula ⇒
480×10×10
1
4
=
(480+y)×20×8
3
4
⇒
480×10×10
1
=
160(480+y)
3
⇒480+y=900 ⇒y=(900−480)=420 ∴ The required number of persons is 420.