14
Q:

# A can do a certain work in the same time in which B and C together can do it.If A and B together could do it in 20 days and C alone in 60 days ,then B alone could do it in:

 A) 20days B) 40 days C) 50 days D) 60 days

Explanation:

(A+B)'s 1 day's work=1/20

C's 1 day work=1/60

(A+B+C)'s 1 day's work=$\inline&space;{\color{Black}&space;\left&space;(&space;\frac{1}{20}&space;+&space;\frac{1}{60}\right&space;)=\frac{4}{60}=\frac{1}{15}}$

Also A's 1 day's work =(B+C)'s 1 day's work

$\inline&space;{\color{Black}&space;\therefore&space;}$ we get: 2 * (A's 1 day 's work)=1/15

=>A's 1 day's work=1/30

$\inline&space;{\color{Black}&space;\therefore&space;}$ B's 1 day's work= $\inline&space;{\color{Black}&space;\left&space;(&space;\frac{1}{20}&space;-\frac{1}{30}\right&space;)=\frac{1}{60}}$

So, B alone could do the work in 60 days.

Q:

Amar can do a piece of work in 10 days. He works at it for 4 days and then Arun finishes it in 9 days. In how many days can Amar and Arun together finish the work ?

 A) 4 days B) 8 days C) 3 days D) 6 days

Explanation:

4/10 + 9/x = 1

=> x = 15

Then both can do in

1/10 + 1/15 = 1/6

=> 6 days

2 39
Q:

12 men complete a work in 9 days. After they have worked for 6 days, 4 more men join them. How many days will they take to complete the remaining work ?

 A) 2 days B) 2.5 days C) 2.25 days D) 3 days

Explanation:

1 man's 1 day work = 1/108
12 men's 6 day's work = 1/9 x 6 = 2/3

Remaining work = 1 - 2/3 = 1/3

16 men's 1 day work = 1/108 x 16 = 4/27
4/27 work is done by them in 1 day.

1/3 work is done by them in 27/4 x 1/3 = 9/4 days.

2 97
Q:

P alone can complete a piece of work in 6 days. Work done by Q alone in one day is equal to one-third of the work done by P alone in one day. In how many days can the work be completed if P and Q work together  ?

 A) 5 (2/3) B) 6 (3/4 ) C) 4 (1/2) D) 3

Explanation:

Work done by P alone in one day = 1/6th of the total work done by Q alone in one day = 1/3(of that done by P in one day) = 1/3(1/6 of the total) = 1/18 of the total.

Work done by P and Q, working together in one day = 1/6 + 1/18  = 4/18 = 2/9 of the total

They would take 9/2 days = 4 (1/2) days to complete the work working together.

1 41
Q:

A can do a piece of work in 30 days. He works at it for 6 days and then B finishes it in 18 days. In what time can A and B together it ?

 A) 14 1/2 days B) 11 days C) 13 1/4 days D) 12 6/7 days

Explanation:

Let 'B' alone can do the work in 'x' days

6/30 + 18/x = 1
x = 22.5
1/30 + 1/22.5 = 7/90

=> 90/7 = 12 6/7 days

5 145
Q:

Two persons K and L can complete a piece of work in 30 days and 45 days respectively. If they work together, what part of the work will be completed in 3 days ?

 A) 1/6 B) 1/3 C) 2/3 D) 1/18