40 Time and Work Questions for CAT with Answers


Question 16:
If A and B can do a piece of work in 8 days, B and C in 12 days and C and A in 16 ‘' days, then in how many days will C finish it when working alone?
[1] 80 days
[2] 36 days
[3] 96 days
[4] 88 days

Answer:

Option: 3

Explanation:

(A + B)'s one day's work = 1/8, (B + C)'s one day's work = 1/12.

(A +C)'s one day's work = 1/16. Add up all the three equations, we get

=> 2(A + B + C)'s one day's work = 1/8 + 1/12 + 1/16 = 26/96.

=> (A + B + C)'s one day's work = 26/192.

=>A's one day's work = (A + B + C)'s one day's work — (B + C)'s one day's

work = 26/192 — 1/12 = (26 — 16)/192 = 10/192.

Since A completes 10/192 of the work in 1 day, he will complete the work in 192/10 = 19.2 days. By a similar logic, B will require 13.7 days and C will require 96 days.


Question 17:
A is twice as good a workman as B and together they finish a piece of work in 20 p days. In how many days can A alone finish the work?
[1] 30 days
[2] 25 days
[3] 20 days
[4] 32 days

Answer:

Option: 1

Explanation:

A's one day's work : B's one day's work = 2 : 1.

=>Out of every three parts of work done, 2 will be done by A and 1 by B

Now, (A B)'s one day's work = 1/20.

A's share = 2/3 x 1/20 = 2/60 = 1/30.

=>In 1 day, A does 1/30 of the work. Hence, A will need a total of 30 days to do the job alone.


Question 18:
The rates of working of A and B are in the ratio 4 : 5. What is the ratio of the number of days taken by them to finish a job when working separately?
[1] 2 : 3
[2] 3 : 2
[3] 5 : 4
[4] 4 : 3

Answer:

Option: 3

Explanation:

The Time Taken is always inversely proportional to the Efficiencies (or the Rates of Working) = time taken by A : B = 5 : 4.


Question 19:
Ram can do a piece of work in 20 days which Shyam can do in 30 days. They begin together with the condition that Ram shall leave the job 3 days before the actual completion of work. What is the total number of days required to complete the work?
[1] 14 days
[2] 19 days
[3] 27 days
[4] 9 days

Answer:

Option: 1

Explanation:

Let X be the days required to complete the work \( \frac{{x - 3}}{{20}} + \frac{x}{{30}} = 1\)

Solving \(x\approx 14\)


Question 20:
Rama can do a piece of work in 10 days and Rami alone can do it in 5 days. Rama and Rami undertook to do it for Rs.400. With the help of their neighbour Snooty, they finished it in 2 days. The share of Snooty out of the remuneration is
[1] Rs.120
[2] Rs.200
[3] Rs.160
[4] Rs.180

Answer:

Option: 3

Explanation:

(Rama + Rami + Snooty)'s one day's work = 1/10 + 1/5 + 1/X.

(Rama + Rami + Snooty)'s two day's work = 2 x (1110 + 1/5 + 1/X).

{because they need 2 days to do the job)

=> 2 [ 1/10 + 115 + 1/X ] = 1 = On solving we get, X = 5 days.

This means that Snooty can do the whole work alone in 5 days.

=> In one day, he does 1/5 of the work.

=>In two days, he does (2 x 1/5) of the work.

=> Snooty's share = 1/5 x 2 x 400 = Rs.160.


Time and Work


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