Time and Work Questions

Let M, N and O worked together for x days.

From the given data,
M alone worked for 8 days
M,N,O worked for x days
N, O worked for 1 day

But given that
M alone can complete the work in 18 days
N alone can complete the work in 36 days
O alone can complete the work in 54 days

The total work can be the LCM of 18, 6, 54 = 108 units

M's 1 day work = 108/18 = 6 units
N's 1 day work = 108/36 = 3 units
O's 1 day work = 108/54 = 2 units

Now, the equation is
8 x 6 + 11x + 5 x 1 = 108
48 + 11x + 5 = 108
11x = 103 - 48
11x = 55
x = 5 days.

Hence, all M,N and O together worked for 5 days.

Given that,

 working days = 5

 working hours = 8

 A man get rupess per hour is Rs.2.40

 So in one day the man get total rupees is 2.40 x 8 = 19.2

 So in 5 days week the man get total rupees is 19.2 x 5 = 96

 So in 4 week the man get total rupees is 96 x 4 = 384

 So the man worked for = 160hours in 4 weeks

 But given that the man earned Rs.432

 Hence remaning money is (432-384 = 48)which is earn by doing overtime work

Overtime hours  = 48/3.20 = 15

So total worked hours is = 15 + 160 = 175.

3/15 + 4/16 + x/24 = 1

⇒x=1315

Ratio of times taken by A and B = 160 : 100
A can do the work in 12 days
Let B can do the work in "D" days
=> 160:100 = 12 : D
=> D = 12 x 100/160 = 7.5 hrs

Let the number of days be 'p' 

As the work is same, we know that

M1 x D1 x H1 = M2 x D2 x H2

Where M = Men, D = Days, H = Hours per day 

Here M1 = 9, D1 = 15, H1 = 7 

M2 = 6, D2 = p, H2 = 9 

=> 9 x 15 x 7 = 6 x p x 9 

=> p = 35/2 = 17.5 days.

M = 10 days

The ratio of efficiency of M & N are 3 : 2

Hence, the time rquired for N alone = 15 days

=> Required time taken t=by both to complete the work = M x N / M + N 

= 10 x 15/ 10 + 15

= 150/25

= 6 days.