Kareena can do a piece of work in 9 days and Krishna can do the same work in 18 days. They started the work. After 3 days Shahid joined them, who can complete alone the same whole work in 3 days. What is the total No. of days in which they had completed the work?

Krishna's efficiency = 10%
Mohan's efficiency = 5%
Work done by Krishana and mohan together in 3 days = 15 x 3 = 45%
Now, number of days in which B completed rest (55%) work alone = 55/5 = 11
Total No. of days in which B worked = 3 + 11 = 14
Now No. of days required by B, when A and B both worked together = 100/15 = 6²/₃
? Required difference in No. of days = (11) - (6²/₃)
= 13/3 = 4 1/3 days

Efficiency (Asha : Usha) = 5 : 4
Number of days(Asha : Usha) = 4x : 5x = 4x : 25
? Number of days required by Asha to finish the work alone = 4x
= 4 x 5 = 20.
Now, since Asha and Usha did work together for last 5 days = 5 x 9 = 45%
(since efficiency of Asha = 5% and Usha's efficiency = 4%)
It means Asha completed 55% work alone.
? No. of days taken by Asha to complete 55% work = 55/5 = 11days

A's 5 day work = 50%
B's 5 day work = 33.33%
C's 2 day work = 16.66% [100 - (50 + 33.33)]
Ratio of contribution of work of A , B and C = 50 : 33.33 : 16.66 = 3 : 2 : 1
A's total share = Rs. 1500
B's total share = Rs. 1000
C's total share = Rs. 500

A's one day's earning = Rs. 300
B's one day's earning = Rs. 200
and C's one day's earning = Rs. 250

Since, 50 men can do a job in 50 days.
So, work done by 1 man in a day = 1/(50 x 50)

Also, 80 women can do the job in 50 days.
So, work done by 1 women in 1 day = 1/(50 x 80)

Now, work done by 40 men and 48 women in first 10 days
= (40 x 10)/(50 x 50) + (48 x 10)/(50 x 80)
= 4/25 + 3/25 = 7/25

Now, 5 men and 8 women are removed after 10 days,
So work done by 35 men and 40 women in 10 days = (35 x 10)/(50 x 50) + (40 x 10)/(50 x 80)
= 7/50 + 1/10 = (7 + 5)/50
= 6/25

Again, 5 men and 8 women are removed after 10 days,
So work done by 30 men and 32 women in 10 days = (30 x 10)/(50 x 50) + (32 x 10)/(50 x 80) = 5/25

Now, after every 10 days as the number of men and
women decrease, work done also decreased by 1/25th past.
So, work done after every 10 days upto 50 days = 7/25 + 6/25 + 5/25 + 4/25 + 3/25
= 25/25 = 1

So, it will take 50 days for them to complete the work.

By the fundamental of work and time,
x/45 + (x + 23)/40 = 1
? x = 9 days

Efficiency of Kavita = 5%
Efficiency of Babita = 1.66%
Efficiency of Samita = 3.33%
Work done in 5 days by K + B + S = 5 x 10 = 50%
Work done in 3 days by K + B = 3 x 6.66 = 20%
Remaning work (30%) done by Kavita alone = 30/5 = 6 days

M₁ = 250, D ₁ = 33 days
per day meal W₁ = W₂ = 125 g
M₂ = (250 + 80) =330 and D₂=?
According to the formula
M₁D₁W₂ = M₂D₂W₁
250 x 33 x 125 = 330 x D₂x 125
? D₂ = (250 x 33)/330
? D₂ = 25 days

Let the original number of men = N
Time taken by N = 80 days
Now, (N - 10) men can finish the work in the (80 + 20) = 100 days
Here, M₁ = N, M₂ = (N - 10), D₁ = 80 and D₂ = 100
According to the formula.
M₁D₁ = M₂D₂
? N x 80 = 100 x (N - 10)
? 8N = 10N - 100
? 10N - 8N = 100
? N = 50

A's 1 days 's work = 1/8
B ' s 1 days ' s = 1/10
C ' s day 's work = 1/20
(A + B + C)'s 1 days 's work = 1/8 + 1/10 + 1/20 = (5 + 4 + 2)/40 = 11/40
? (A + B + C ) can finish the work in 40/11 days or 3 ⁷/₁₁ days.

10 day's work by 15 men = 10/210 = 1/21
At the end of every 10 days 15 additional men are employed i.e., for the next 10 days we have 15 + 15 = 30 men
? Next 10 day's work by 30 men = 2/21
Hence in 20 days only (1/21 + 2/21) = 3/21 work is completed
To complete the whole work we have to reach the value of (21/21) work.
Now, (1/21) + (2/21) + (3/21) + ......... (6/21) = 21/21 = 1
Hence total time to complete the whole wok 10 + 10 + 10 + 10 + 10 + 10 = 60 days