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- Question
A is thrice efficient as B and C is twice as efficient as B. what is the ratio of number of days taken by A,B and C, when they work individually?
Options- A. 2:6:3
- B. 2:3:6
- C. 1:2:3
- D. 3:1:2
- Correct Answer
- 2:6:3
ExplanationA : B : C
Ratio of efficiency 3 : 1 : 2
Ratio of No.of days 1/3 : 1/1 : 1/2
or 2 : 6 : 3
Hence A is correct.
- 1. A is twice efficient as B and together they do the same work in as much time as C and D together. If C and D can complete the work in 20 and 30 daysrespectively, working alone ,then in how many days A can complete the work individually:
Options- A. 12 days
- B. 18 days
- C. 24 days
- D. 30 days Discuss
- 2. 3 men, 4 women and 6 children can complete a work in 7 days. A woman does double the work a man does and a child does half the work a man does. How many women alone can complete this work in 7 days ?
Options- A. 6
- B. 9
- C. 5
- D. 7 Discuss
- 3. An air conditioner can cool the hall in 40 miutes while another takes 45 minutes to cool under similar conditions. If both air conditioners are switched on at same instance then how long will it take to cool the room approximately ?
Options- A. 18 minutes
- B. 19 minutes
- C. 22 minutes
- D. 24 minutes Discuss
- 4. (x-2) men can do a piece of work in x days and (x+7) men can do 75% of the same work in (x-10)days. Then in how many days can (x+10) men finish the work?
Options- A. 27 days
- B. 12 days
- C. 25 days
- D. 18 days Discuss
- 5. A group of workers was put on a job. From the second day onwards, one worker was withdrawn each day. The job was finished when the last worker was withdrawn. Had no worker been withdrawn at any stage, the group would have finished the job in 55% of the time. How many workers were there in the group?
Options- A. 50
- B. 40
- C. 45
- D. 10 Discuss
- 6. A and B can do a work in 4 hours and 12 hours respectively. A starts the work at 6 AM and they work alternately for one hour each. When will the work be completed?
Options- A. 4 days
- B. 5 days
- C. 6 days
- D. 7 days Discuss
- 7. A is 30% more efficient than B. How much time will they, working together, take to complete a job which A alone could have done in 23 days ?
Options- A. 9 days
- B. 11 days
- C. 13 days
- D. 15 days Discuss
- 8. Two pipes A and B can fill a tank in 24 hours and 1717 hours respectively. Harihar opened the pipes A and B to fill an empty tank and some times later he closed the taps A and B , when the tank was supposed to be full. After that it was found that the tank was emptied in 2.5 hours because an outlet pipe "C" connected to the tank was open from the beginning. If Harihar closed the pipe C instead of closing pipes A and B the remaining tank would have been filled in :
Options- A. 2 hours
- B. 8 hours
- C. 6 hours
- D. 4 hours Discuss
- 9. A does half as much work as Band C does half as much work as A and B together. If C alone can finish the work in 40 days, then together ,all will finish the work in ?
Options- A. 17 + 4/7 days
- B. 13 + 1/3 days
- C. 15 + 3/2 days
- D. 16 days Discuss
- 10. There are three boats B1, B2 and B3 working together they carry 60 people in each trip. One day an early morning B1 carried 50 people in few trips alone. When it stopped carrying the passengers B2 and B3 started carrying the people together. It took a total of 10 trips to carry 300 people by B1, B2 and B3. It is known that each day on an average 300 people cross the river using only one of the 3 boats B1, B2 and B3. How many trips it would take to B1, to carry 150 passengers alone?
Options- A. 15
- B. 30
- C. 25
- D. 10 Discuss
Time and Work problems
Search Results
Correct Answer: 18 days
Explanation:
A + B = C + D
| | | |
Ratio of efficiency 10x + 5x 9x + 6x
|________| |_________|
15x 15x
Therefore , ratio of efficiency of A:C =10:9
Therefore, ratio of days taken by A:C = 9:10
Therefore, number of days taken by A = 18 days
Correct Answer: 7
Explanation:
Let 1 woman's 1 day work = x.
Then, 1 man's 1 day work = x/2 and 1 child's 1 day work x/4.
So, (3x/2 + 4x + + 6x/4) = 1/7
28x/4 = 1/7 => x = 1/49
1 woman alone can complete the work in 49 days.
So, to complete the work in 7 days, number of women required = 49/7 = 7.
Correct Answer: 22 minutes
Explanation:
Let the two conditioners be A and B
'A' cools at 40min
'B' at 45min
Together = (a x b)/(a + b)
= (45 x 40)/(45 + 40)
= 45 x 40/85
= 21.1764
= 22 min (approx).
Correct Answer: 12 days
Explanation:
=> x= 20 and x=-14
so, the acceptable values is x=20
Therefore, Total work =(x-2)x = 18 x 20 =360 unit
Now 360 = 30 x k
=> k=12 days
Correct Answer: 10
Explanation:
Let the number of workers be x.
Now, Using work equivalence method,
X + (X-1) + (X-2)+ . . . . + 1 = X *55% of X
=> [X * (X+1)] / 2 = X * (55X/100) [because, Series is in AP. Sum of AP = {No. of terms (first term+ last term)/2} ]
Therefore, X = 10
Correct Answer: 6 days
Explanation:
Work donee by A and B in the first two hours, working alternatively = First hour A + Second hour B = (1/4) + (1/12) = 1/3.
Thus, the total time required to complete the work = 2 (3) = 6 days
Correct Answer: 13 days
Explanation:
Ratio of times taken by A and B = 100 : 130 = 10 : 13.
Suppose B takes x days to do the work.
Then, 10 : 13 :: 23 : x => x = ( 23 x 13/10 ) => x = 299 /10.
A's 1 day's work = 1/23 ;
B's 1 day's work = 10/299 .
(A + B)'s 1 day's work = ( 1/23 + 10/299 ) = 23/299 = 113 .
Therefore, A and B together can complete the work in 13 days.
Correct Answer: 8 hours
Explanation:
Efficiency of Inlet pipe A = 4.16%
Efficiency of Inlet pipe B = 5.83%
Therefore, Efficiency of A and B together = 100 %
Now, if the efficiency of outlet pipe be x% then in 10 hours the capacity of tank which will be filled = 10 * (10 - x)
Now, since this amount of water is being emptied by 'C' at x% per hour, then
=> x = 8
Therefore, in 10 hours 20% tank is filled only. Hence, the remaining 80% of the capacity will be filled by pipes A and B in 80/10 = 8 hours
Correct Answer: 13 + 1/3 days
Explanation:
C alone can finish the work in 40 days.
As given C does half as much work as A and B together
=> (A + B) can do it in 20 days
(A + B)s 1 days wok = 1/20.
A's 1 days work : B's 1 days Work = 1/2 : 1 = 1:2(given)
A's 1 day?s work = (1/20) x (1/3) = (1/60) [Divide 1/20 in the raio 1:2]
B's 1 days work = (1/20) x (2/3) = 1/30
(A+B+C)'s 1 day's work = (1/60) + (1/30) + (1/40) = 9/120 = 3/40
All the three together will finish it in 40/3 = 13 and 1/3 days.
Correct Answer: 15
Explanation:
Combined efficiency of all the three boats = 60 passenger/trip
Now, consider option(a)
15 trips and 150 passengers means efficiency of B1 = 10 passenger/trip
which means in carrying 50 passengers B1 must has taken 5 trips. So the rest trips equal to 5 (10-5 = 5) in which B2 and B3 together carried remaining 250 (300 - 50 = 250) Passengers.
Therefore the efficiency of B2 and B3 = 250/5 = 50 passenger/trip
Since, the combined efficiency of B1, B2 and B3 is 60. Which is same as given in the first statement hence option(a) is correct.
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