10:09
TIME AND WORK
If M1 person can do W1 work in D1 days and M2 person can do W2 works in D2 days then we can say M1 D1 W2 = M2 D2 W1
For Time T
M1 D1 T1 W2 = M2 D2 T2 W1
For Efficiency E
M1 D1 T1 E1 W2 = M2 D2 T2 E1 W1
The Only exchange in formula is work W
If A can do a piece of work in n days,Then the works done by a in one day =1 / N
If A one day work is 1 / N the work finished by A in N days
A is 4 times Eficien then B==>4A=B
A:B=4:1
If A can do a work in D1 days and B can do the same work in D2 days then A and B together can do the same work in
(D1 * D2) / (D1 + D2)
If A can do a piece of work in D1 days,B can do in D2 days C in D3 days then together the same work in
(D1+D2+D3) / (D1D2 +D2D3+D3D1)
If A and B can do piece of work in D1 alone D2,B alone Can=?
(D1*D2) / (D2-D1)
If the number of men are changed in ratio M:N the time taken to complete the work will change in the ratio N:M
Eg:
A can do a piece of work in 14 days which b can do in 21 days.They begin together but 3 days before the completion the work ,A leaves off.The total number of days to complete the work is?
A=14 Days
B=21 Days
Total work=LCM(14,21)
=42
A's One day work=42/14=3
B's One day work=42/21=2
A+B One day work =5
Before 3 days A leaves=42-3=39
39 work done by A+B=39/5=7.8
total working days=7.8+remaining days=10.8
