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07 Jan 2020, 06:08
Kudos
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C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
78% (02:47) correct
22%
(02:44)
wrong
based on 137
sessions
History
Date
Time
Result
Not Attempted Yet
Three taps A, B and C can fill a tank individually in 10 hrs, 20 hrs and 25 hrs respectively. At first all the taps are opened simultaneously. After 2 hours tap C is closed and after further 2 hours tap B is also closed. Tap A is kept open till the tank gets completely filled. What fraction of the tank is filled by tap A?
A. 2/11
B. 9/11
C. 18/25
D. 7/25
E. 1/2
A. 2/11
B. 9/11
C. 18/25
D. 7/25
E. 1/2
Archit3110
13 Jan 2020, 09:17
Kudos
Bookmarks
work of C = 2/25
work of B = 4/20 ; 1/5
total work done ; 7/25
left with 18/25
A has to do 18/25
IMO C
work of B = 4/20 ; 1/5
total work done ; 7/25
left with 18/25
A has to do 18/25
IMO C
Bunuel
14 Jan 2020, 07:55
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Bunuel
Let the capacity of the Tank be 100 units
Efficiency of Tap A = 10 Units/Hr
Efficiency of Tap B = 5 Units/Hr
Efficiency of Tap C = 4 Units/Hr
Combined efficiency of the 3 taps is 19 Units/Hr
Water filled up in 2 Hours is 38 Units ; We are left with 62 Units
After 2 Hours C is closed and A and B works at efficiency of 15 Units/Hr , so in 2 Hours they fill up 30 Units; We are left with 32 Units
Next B is also closed and we are left with Tap A to fill up 32 units
Thus, Part of work done by Tap A is 2*10 + 2*10+32 = 72 units out of 100 Units
SO, A does 18/25 part of the job, Answer must be C
