__1. X is twice good a workman as Y and together they finish a piece of work in 18 days. In how many days will X alone finish the work ?__

__Solution__ - According to the condition given if **X is twice good a workman as Y then the time taken by X to finish a particular work would be half of the time taken by Y to finish the same work.**

**So if we suppose that Y takes 2k days to finish a work then X would take k days to finish the same work.**

**Solving, 1/(2k) + ****1/(k)**** = 1/18**

**k = 27 days **

__Answer - X would finish the work in 27 days.__

__2. If 10 men complete a work in 12 days. How many days would be taken by 18 men to complete the same work ?__

__Solution__ - Suppose the time taken by **18 men to complete the same work is t days.**

**Using the concept of Mandays - **

**10*12 = 18*t**

**t = 20/3 days**

**Answer - ****18 men would take 20/3 days to complete the same work.**

__3. If 100 men can do 100 jobs in 100 days, 1 men can do one job in how many days ?__

**Solution - Using the concept M*D = W**

*(100*100)/(1*D) = 100/1*

*Solving we get D = 100 days*

__Answer - 1 men can do one job in 100 days.__

__4. 1 man or 2 boys or 3 girls can do a piece of work in 121 days. In how many days can one man, one girl and one boy do the same work ?__

__Solution - Let one man does m units of work in 1 day.__

**Let one boy does b units of work in 1 day.**

**Let one girl does g units of work in 1 day.**

**So 1m*121 = 2b*121 = 3g*121 = W, where W is the total units of work.**

**m = W/121 , b= W/242 , g = W/ 363**

**So 1**** man, 1 girl and 1 boy can do the same work in (W) / ((W/121) + ****(W/242) + ****(W/363)****) = 66**

*Answer - ***So 1**** man, 1 girl and 1 boy can do the same work in 66 days.**

__5. If the ratio of work efficiency of P & Q is 6:5 and that of Q & R is 6:5. If P can complete the piece of work in 2 days, In how many days the same work can be completed by Q & R separately ?__

**Solution - If the ****work efficiency of P & Q is 6:5 then time taken would be in the ratio 5:6**

**If the ****work efficiency of Q & R is 6:5 then time taken would be in the ratio 5:6**

*Let the time taken by P = 5K and by Q = 6K, where K is some constant.*

*5K = 2, So 6K = 12/5 Days*

__So the time taken by Q to complete the work is 12/5 days__

*Now **let the time taken by Q = 5X and by R = 6X, **where X is some constant.*

*Q = 12/5 days, So R = 72/25 days*

__Answer - So the time taken by R to complete the work is 72/25 days.__