1. P is able to do a piece of work in 15 days and Q can do the same work in 20 days. If they can work together for 4 days, what is the fraction of work left?

1. 8/15

2. 7/15

3. 11/15

4. 2/11

Answer & Explanation

Answer:- 1

Explanation :-

P’s 1 day Work = 1/15, Q’s 1 day Work = 1/20

1 day Work of both P & Q together = (1/15) + (1/20) = 7/60

Work that P & Q together do in 4 days = 4 * (7/60) = 7/15

Work left = 1 – 7/15= 8/15

2. P can lay railway track between two stations in 16 days. Q can do the same job in 12 days. With the help of R, they completes the job in 4 days. How much days does it take for R alone to complete the work?

1. 9(3/5) days

2. 9(1/5) days

3. 9(2/5) days

4. 10 days

Answer & Explanation

Answer:- 1

Explanation :-

P’s 1 day Work = 1/12, Q’s 1 day Work = 1/16

Work that P, Q & R can together do in 1 day = 1/4

R’s 1 day Work = 1/4 – [(1/16) + (1/12)] = [12 -( 4 + 3)] /48= 5/48

Therefore, R alone can complete the work in 48/5 days = 9 and (3/5) days

3. P, Q and R can do a work in 20, 30 and 60 days respectively. How many days does it need to complete the work if P does the work and he is assisted by Q and R on every third day?

1. 10 days

2. 14 days

3. 15 days

4. 9 days

Answer & Explanation

Answer:- 3

Explanation :-

P’s 1 day Work = 1/20, Q’s 1 day Work = 1/30, R’s 1 day Work = 1/60

P’s 2 day work = 2*(1/20) = 1/10

At every third day they work together, therefore

Work done by P,Q & R at every third day = (1/20) + (1/30) + (1/60) = 1/10

Work done in 3 days = (1/10) + (1/10) = 1/5

Whole work will be done in = (3 x 5) = 15 days.

4. A is thrice as good as B in work. A is able to finish a job in 60 days less than B. They can finish the work in – days if they work together.

1. 18 days

2. 22 ½ days

3. 24 days

4. 26 days

Answer & Explanation

Answer:- 2

Explanation :-

Let A can complete the work in x days ,

Therefore, B can complete the same work in 3x days

3x – x = 60 days, therefore, x = 30 days 3x = 90 days

A’s 1 day Work = 1/30, B’s 1 day Work = 1/90,

Work that A & B together do in 1 days = (1/30) + (1/90) = 2/45

Therefore, A & B together can do the work in 45/2 days = 22 ½ days

5. A can do a particular work in 6 days . B can do the same work in 8 days. A and B signed to do it for Rs. 3200. They completed the work in 3 days with the help of C. How much is to be paid to C?

1. Rs. 380

2. Rs. 600

3. Rs. 420

4. Rs. 400

Answer & Explanation

Answer:- 4

Explanation :-

A’s 1 day Work = 1/6, Q’s 1 day Work = 1/8

Work that P, Q & R can together do in 1 day = 1/3

C’s 1 day Work = 1/3 – [(1/6) + (1/8)] = [8 – (4 + 3)]/24 = 1/24

A’s 1 day Work** :** B’s 1 day Work **:** C’s 1 day Work

= 1/6** :** 1/8 **:** 1/24 = 4 **:** 3 **:** 1

Amount paid to C = (3200/8) × (1) = 400