Time and Work

1. A can eat 10 burgers in 2 days and B can eat 20 burgers in 1 day. For how long will 250 burgers last is both start eating them together? [CDS 2000]

(a) 25 days

(b)  20 days

(c) 10 days

(d) none of these

Answer: (c)

Explanation:

A can eat 5 burgers in 1 day and B can eat 20 burgers in 1 day

A and B together can eat 25 burgers in 1 day

=>They can eat 250 burgers in 10 days.


2. A can do a piece of work in 12 days, and B can do the same in 15 days. In how many days can both do it?

(a) 5

(b) 

(c) 

(d)

Answer: (c)

Explanation:

If A can do a piece of work in n days, then A’s one day’s workpart

A’s 1 days work partpart

B’s 1 day’s workpart part

(A+B)’s 1 day’s work       [L.c.m of 12 and 15=60]

If A+B’s one day’s work is then A+B can finish the work in n days

So, A and B together can finish the work in  days


3. A and B together can do a piece of work in 24 days, which B and C together can do a piece of work in 32 days. A, B started the work, C replaced A after 10 days, B and C worked for 4 more days and B left the work. C finished the work in 26 days after A left. In how many days C alone will do the work?

(a) 22 days

(b) 50 days

(c) 48 days

(d)

Answer: (c)

Explanation:

A’s 10 days work + B’s 14 days work + C’s 26 days work=1

(A+B)’s 10 days work + (B+C)’s 4 days work + C’s 22 days work=1

Therefore, C alone can finish the work in 48 days.


4. A can do a piece of work in 14 days which can do in 21 days. They begin together but 3 days before the completion of the work, A leaves of. The total number of days to complete the work is:

(a) 

(b) 

(c) 

(d)

Answer: (c)

Explanation:


5. A is twice as efficient as B and therefore is able to finish a job in 30 days less than B Working together, they can do it in:

(a) 15 days

(b) 10 days

(c) 60 days

(d) 30 days

Answer: (d)

Explanation:

Ratio of times taken by A and B=1:2

If difference of time is 1 day, B takes 2 days

If difference of time is 30 days B takes (2×30) =60 days

So, A takes 30 days to do the work

If A can do a piece of work in n days, then A’s one day’s work

Therefore, A and B together can do the work in 20 days.


6. A is thrice as good a workman as B and together they finish a piece of work in 10 days. The number of days taken by A alone to finish the work is:

(a) 

(b) 

(c) 14 days

(d)

Answer: (a)

Explanation:

Ratio of times taken by A and B=1:3

A’s 1 day’s work : B’s 1 day’s work=3:1

Let A’s and B’s 1 day’s work be 3x and x respectively


7. John and Ben working separately can assemble a computer in 10 hrs and 12 hrs respectively. If they are working for 1 hr alternately john beginning, in how many hours will the computer be assembled?

(a) 10 hours

(b) 

(c) 

(d)

Answer: (b)

Explanation:

After 10 hours of combined, but working we get the part of computer= John’s 5 hours work + Alternate Ben’s 5 hours work

Now, at the start of 11th hour, John will work


8. If one man or two women or three boys can finish a work in 88 days, then how many days will one man, one women and one boy together take to finish the same work?

(a) 46 days

(b) 54 days

(c) 48 days

(d) 44 days

Answer: (c)

Explanation:

1 man work=3 boys work

2 women work=1 man work

2 women work=3 boys work

1 man can finish a work in 88 days


9. 5 men can complete a piece of work in 4 days. In how many days can 8 men complete the same work?

(a) 14 days

(b) 8 days

(c) 32 days

(d) 2  1/2 days

Answer: (d)

Explanation:

Suppose 8 men complete the same work in x days.

8:5::4:x

8 ×x=5 ×4


10. 12 men can complete a piece of work in 4 days, while 15 women can complete the same work in 4 days. 6 men start working on the job and after working for two days, all of them stopped working. How many women should be put on the job to complete the remaining work, if it is to be completed in 3 days?

(a) 15

(b) 18

(c) data inadequate

(d) none of these

Answer: (a)

Explanation:

12 M or 15W complete the work in 4 days

=> x= 1/4 th work

Remaining work = 3/4 th.

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