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27 Apr 2021, 06:00
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47% (02:08) correct
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8 men can dig a pit in 20 days. If a man works half as much as a boy, then 4 men and 9 boys can dig a similar pit in:
(A) 10 days
(B) 12 days
(C) 15 days
(D) 16 days
(E) 18 days
(A) 10 days
(B) 12 days
(C) 15 days
(D) 16 days
(E) 18 days
27 Apr 2021, 06:09
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Bunuel
8 men can dig a pit in 20 days. If a man works half as much again as a boy, then 4 men and 9 boys can dig a similar pit in:
(A) 10 days
(B) 12 days
(C) 15 days
(D) 16 days
(E) 18 days
(A) 10 days
(B) 12 days
(C) 15 days
(D) 16 days
(E) 18 days
CONCEPT: \(\frac{(Machine_Power * Time)}{Work} = Constant\)
i.e. \(\frac{(M_1 * T_1)}{W_1} = \frac{(M_2 * T_2)}{W_2}\)
i.e. \(\frac{(M_1 * T_1)}{W_1} = \frac{(M_2 * T_2)}{W_2}\)
1 men = 1.5 boy
8 men = 8*1.5 = 12 boys
i.e. 4 men and 9 boys = 4*1.5+9 = 15 boys
i.e. \(\frac{(12 * 20)}{1} = \frac{(15 * T_2)}{1}\)
ie.. \(T_2 = \frac{12*20}{15} ≈ 16\) days
Answer: Option D
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27 Apr 2021, 06:41
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Let men be m and boys be b
8/m = 1/20 therefore m = 160 (ie 1 man will dig the same hole in 160 days)
as m = 1.5b
it will take 1 boy 240 days to dig the same hole.
Question asks for how long it will take 4 men and 9 boys to dig a hole, which is the same as asking how long will it take 15 boys (given that 4m = 6b) to dig the same hole.
15/240 = 1/n
15n = 240
n = 16
Answer D.
8/m = 1/20 therefore m = 160 (ie 1 man will dig the same hole in 160 days)
as m = 1.5b
it will take 1 boy 240 days to dig the same hole.
Question asks for how long it will take 4 men and 9 boys to dig a hole, which is the same as asking how long will it take 15 boys (given that 4m = 6b) to dig the same hole.
15/240 = 1/n
15n = 240
n = 16
Answer D.
