Time and Work Questions

FACTS  AND  FORMULAE  FOR  TIME  AND  WORK  QUESTIONS

 

 

1. If A can do a piece of work in n days, then A's 1 day's work =1n

2. If A’s 1 day's work =1n, then A can finish the work in n days.

 

3. A is thrice as good a workman as B, then:

Ratio of work done by A and B = 3 : 1.

Ratio of times taken by A and B to finish a work = 1 : 3.

 

NOTE : 

Efficiency1No of time units

 

 Efficiency × Time = Constant Work

 

Hence, Required time = WorkEfficiency

 

Whole work is always considered as 1, in terms of fraction and 100% , in terms of percentage.

In general, number of day's or hours = 100Efficiency

Q:

A single reservoir supplies the petrol to the whole city, while the reservoir is fed by a single pipeline filling the reservoir with the stream of uniform volume. When the reservoir is full and if 40,000 liters of petrol is used daily, the suply fails in 90 days.If 32,000 liters of petrol is used daily, it fails in 60 days. How much petrol can be used daily with out the supply ever failing? 

A) 64000 liters B) 56000 liters
C) 78000 liters D) 60000 liters
 
Answer & Explanation Answer: B) 56000 liters

Explanation:

Let x liter be the per day filling and v litr be the capacity of the reservoir, then 

      90x + v = 40000 * 90     -----(1)

      60x + v= 32000 * 60     ------(2)

solving eq.(1) and (2) , we get

      x = 56000

Hence , 56000 liters per day can be used without the failure of supply.

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8 8355
Q:

A contractor undertake to finish a certain work in 124 days and employed 120 men. After 64 days, he found that he had already done 2/3 of the work. How many men can be discharged so that the work may finish in time ? 

A) 64 B) 62
C) 58 D) 56
 
Answer & Explanation Answer: D) 56

Explanation:

Days remaining 124 – 64 = 60 days

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

Let men required men for working remaining days be 'm'

So men required = (120 x 64)/2 = (m x 60)/1 => m = 64

Men discharge = 120 – 64 = 56 men.

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15 8189
Q:

Twenty men can do a work in eighteen days. Eighteen women can complete the same work in fifteen days. What is the ratio between the capacity of a woman and a man ?

A) 4:5 B) 3:4
C) 4:3 D) 2:3
 
Answer & Explanation Answer: C) 4:3

Explanation:

(20 x 18) men can complete the work in in one day.

one man's one day work = 1/360

(18 x 15) women can complete the work in 1 day

1 woman's one day work = 1/270

So, required ratio = 1270:1360= 4:3

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13 7998
Q:

P alone can do a piece of work in 24 days. The time taken by P to complete one-third of work is equal to time taken by Q to complete half of the work. How many days are required to complete by P and Q working together ?

A) 9 3/5 days B) 7 days
C) 6 3/7 days D) 8 days
 
Answer & Explanation Answer: A) 9 3/5 days

Explanation:

Let the total work be 'W'

As per the given information,

P can complete the work 'W' in 24 days.

=> one day work of P = W/24

And also given that,

The time taken by P to complete one-third of work is equal to time taken by Q to complete half of the work

=> PW/3 = QW/2

=> P's

1 day =    W/24

   ?    =      W/3

=>  ?  = 24W/3W  = 8

=> QW/2 = 8 days

=> Q alone can complete the work W in 16 days

=> P + Q can complete the work in

1/24 + 1/16 = 5/48

=> 48/5 days = 9 3/5 days.

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18 7991
Q:

A contractor undertook to complete a piece of work in 120 Days and employed 140 men upon it. At the end of 66 days only half of the work was done,so he put on 25 extra men. By how much time did he exceed the specific time ?

A) 2 days B) 3 days
C) 4 days D) 5 days
 
Answer & Explanation Answer: A) 2 days

Explanation:

work done=total number of person x number of days;
half of work done = 140 x 66;
For half of remaining work 25 extra men are added.
Therefore, total men for half work remaining = 140 + 25 = 165;
Let 2nd half work will be completed in K days;
140 x 66 = 165 x K
K = 122;
Hence, extra days => 122-120 = 2days.

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12 7728
Q:

X can complete the work in 10 days, Y can do the same in 15 days. If they are hired for 5 days to do the work together, what is the work that left unfinished?

A) 1/3 B) 2/3
C) 1/6 D) 5/6
 
Answer & Explanation Answer: C) 1/6

Explanation:

Given X can do in 10 days 

=> 1 day work of X = 1/10

 

Y can do in 15 days 

=> 1 day work of Y = 1/15

 

1day work of (X + Y) = 1/10 + 1/15 = 1/6

 

Given they are hired for 5 days

 => 5 days work of (X + Y) = 5 x 1/6 = 5/6

 Therefore, Unfinished work = 1 - 5/6 = 1/6 

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11 7620
Q:

45 men working 9 hours per day dig 40 m deep. How many extra men should be put to dig to a depth of 56 m working 7 hours per day ?

A) 36 B) 61
C) 48 D) 54
 
Answer & Explanation Answer: A) 36

Explanation:

(45 x 9)/40 = (M x 7)/56 => M = 81

=> 81 – 45 = 36

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6 7568
Q:

A can do a work in 24 days. B is 20% more efficient than A. If C can do the work in 10 more days than B, find the time taken by A and C together to complete the work.

A) 43/3 days B) 40/3 days
C) 50/3 days D) 41/2 days
 
Answer & Explanation Answer: B) 40/3 days

Explanation:

A takes 24 days to complete a work.
B is 20% more efficient than A,
hence B will take (24*100)/120 = 20 days.
C takes (20+10) = 30 days.
Time taken by A & C in completing the work = (24*30)/(24+30) = (24*30)/54 = 40/3 days.

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