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**Q1. Worker A takes 8 hours to do a job. Worker B takes 10 hours to do the same job. How long should it take both A and B, working together but independently to do the same job.**

a) 40/9

b) 9/40

c) 20/9

d) None of these

A. **(a)**

As discussed in our tutorial

Amount of work done by A in 1 day : 1/8

Amount of work done by B in 1 day : 1/10

Amount of work done by (A+B) :

Both A and B will finish the work in : 40/9 days.

**Q2. Worker A takes 10 hours to do a job. Worker B takes 15 hours to do the same job. How long should it take both A and B, working together but independently to do the same job.**

a) 16

b) 10

c) 6

d) 8

A. **(c)**

As discussed in our tutorial

Amount of work done by A in 1 day : 1/10

Amount of work done by B in 1 day : 1/15

Amount of work done by (A+B) :

Both A and B will finish the work in : 6 days.

**Q3. A and B together can complete a piece of work in 4 days. If A alone can complete the same work in 12 days, in how days can B alone complete that work ?**

a) 9

b) 4

c) 8

d) 6

A. **(d)**

As discussed in our tutorial

Amount of work done by A+B in 1 day : 1/4

Amount of work done by A in 1 day : 1/12

Amount of work done by (B) :

B will finish the work in : 6 days.

**Q4. A and B can do a piece of work in 18 days, B and C can do it in 24 days, A and C can do it in 36 days. In how many days will A finish it, working separately ?**

a) 36

b) 48

c) 18

d) 16

A. **(b)**

Amount of work done by A+B in 1 day : 1/18

Amount of work done by B+C in 1 day : 1/24

Amount of work done by A+C in 1 day : 1/36

On adding above three equations :

2(A + B + C) 1 day work =

(A + B + C) 1 day work :

Hence, it is quite evident that A B & C together can finish the work in 16 days.

Now, A’s 1 day work : (A + B + C) 1 day work – (B + C) 1 day work

So, A alone can finish the work in 48 days.

**Q5. To complete a piece of work A and B take 8 days, B and C 12 days, A, B and C take 6 days. A and C will take :**

a) 9

b) 4

c) 8

d) 6

A. **(c)**

Amount of work done by A+B in 1 day : 1/8

Amount of work done by B+C in 1 day : 1/12

Amount of work done by A+B+C in 1 day : 1/6

Work done by A alone :

(A+B+C)’s 1 day work – (B+C)’s 1 day work = A’s 1 day work

Work done by C alone :

(A+B+C)’s 1 day work – (A+B)’s 1 day work = C’s 1 day work

Now, (A+C)’s 1 day work :

=> 8 days.