If A can do a piece of work in n days, then A's 1 day's work = 1

.

n

2. Days from Work:

If A's 1 day's work =1

,then A can finish the work in n days.

n

3. Ratio:

If A is thrice as good a workman as B, then:

Ratio of work done by A and B = 3 : 1.

Ratio of times taken by A and B to finish a work = 1 : 3.

4. If A is 'x' times as good a workman as B, then he will take of the time by B to do

the same work.

5. A and B can do a piece of work in 'a' days and 'b' days respectively, then working

together, they will take days to finish the work and in one day, they will finish

part of work.

1) Problem: If 9 men working 6 hours a day can do a work in 88 days. Then 6 men

working 8 hours a day can do it in how many days?

Solution: From the above formula i.e (m1*t1/w1) = (m2*t2/w2)

so (9*6*88/1) = (6*8*d/1)

on solving, d = 99 days.

2) Problem: If 34 men completed 2/5th of a work in 8 days working 9 hours a day.

How many more man should be engaged to finish the rest of the work in 6 days

working 9 hours a day?

Solution: From the above formula i.e (m1*t1/w1) = (m2*t2/w2)

so, (34*8*9/(2/5)) = (x*6*9/(3/5))

so, x = 136 men

number of men to be added to finish the work = 136-34 = 102 men

3) Problem: If 5 women or 8 girls can do a work in 84 days. In how many days can

10 women and 5 girls can do the same work?

Solution: Given that 5 women is equal to 8 girls to complete a work. So, 10 women =

16 girls. Therefore 10 women + 5 girls = 16 girls + 5 girls = 21 girls.

8 girls can do a work in 84 days then 21 girls can do a work in (8*84/21) = 32 days.

Therefore 10 women and 5 girls can a work in 32 days

4) Problem: Worker A takes 8 hours to do a job. Worker B takes 10 hours to do the

same job. How long it take both A & B, working together but independently, to do

the same job?

Solution: A's one hour work = 1/8. B's one hour work = 1/10. (A+B)'s one hour work

= 1/8+1/10 = 9/40. Both A & B can finish the work in 40/9 days