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16 Jan 2020, 03:54
Kudos
Bookmarks
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
79% (01:32) correct
21%
(01:44)
wrong
based on 143
sessions
History
Date
Time
Result
Not Attempted Yet
6 labourers can build a wall in 10 days. How many labourers of double the efficiency, are needed to build 3 such walls in 5 days?
A. 10 laborers.
B. 12 laborers.
C. 14 laborers.
D. 16 laborers.
E. 18 laborers.
A. 10 laborers.
B. 12 laborers.
C. 14 laborers.
D. 16 laborers.
E. 18 laborers.
Archit3110
Major Poster
16 Jan 2020, 08:21
Kudos
Bookmarks
from given info
6*10/1 = 2x * 5/3
x= 18 IMO E
6*10/1 = 2x * 5/3
x= 18 IMO E
Bunuel
18 Jan 2020, 13:44
Kudos
Bookmarks
Bunuel
Solution:
The rate of 6 labourers is 1/10 and thus the rate of 1 labourer is (1/10)/6 = 1/60. If a labourer doubles his or her efficiency, a more efficient labourer will have a rate of 1/60 x 2 = 1/30. Let there be n labourers with double efficiency, building 3 walls in 5 days means their combined rate is 3/5. Therefore, we can create the equation:
n x 1/30 = 3/5
n = 3/5 x 30
n = 18
Alternate Solution:
The given statement is that 6 laborers can build one wall in 10 days.
Now, if the efficiency of these 6 laborers were doubled, those 6 laborers could build one wall in just 5 days.
Therefore if one wall can be built in 5 days by the 6 (more efficient) laborers, then in order to build three walls, we would need to triple the number of laborers, so 6 x 3 = 18.
Answer: E
