Efficiency of A = 12.5%
Efficiency of B = 6.25%
Efficiency of C = 1.25%
Efficiency of (A+ B + C) = (12.5 +6.25 + 1.25) = 20%
Required no of days = 100/20 = 5 days
12 men can complete 1/3 of the work in 3 days and the remaining 2/3 of the work in 6 days.
1 man can complete 2/3 of the work in (12 x 6) = 72 days
? (12 - 2 + 6) = 16 men can complete 2/3 of thye work in 72/16 = 41/2 days
? In 12 days work done by 14 men = 1
? In 4 days work done by 14 men = 1 x 4/12 = 1/3
? Remaining work = 1 - 1/3 = 2/3
and number of total men = 14 + 2 = 16
If 1 work is done by 14 men in 12 days
? 2/3 work is done by 16 men in 12 x (14/16) x (2/3) = 7 days
A's 10 day's work = 10 x (1/25) = 2/5
Remaining work = 1 - 2/5 = 3/5
Work was done by (A + B) in 1 day = (1/25 + 1/20) = 9/100
? 3/5 work was done by (A + B) in (100/9 x 3/5) = 20/3 days
Hence, the work lasted for (10 + 62/3) = 162/3 days.
A's 10 day's work = (10 x 1/80) = 1/8
Remaining work = (1 - 1/8) = 7/8
? 7/8 work is done by B in 42 days
? Whole work will be done by B in (42 x 8/7) = i .e., 48 days.
? (A + B)'s day's work = (1/80 + 1/48) = 8/240 = 1/30
Hence, A and B together can finish it in 30 days.
Umesh's 5 day's work = 5 x (1/15) = 1/3
Remaining work = (1 - 1/3) = 2/3
(1/10 + 1/15) work is done by both in 1 day
? 2/3 work is done by both in 6 x (2/3) = 4 days
Hence, the work was completed in 4 + 5 = 9 days.
Efficiency of A = 10%
Efficiency of B = 6.66%
? Required number of days = 100/16.66 = 6 days
Efficiency of A = 100/24 = 4.16%
Efficiency of B = 100/30 = 3.33%
Efficiency of (A+ B+C) =100/12 = 8.33%
? Efficiency of C = (8.33) - (4.16 + 3.33) = 0.83%
? Number of days required by C to complete the work alone
= 100/0.83 = 100/(5/6) = 120 days
(Note : 5/6 = 0.833)
A : B : C
Ratio of efficiency 3 : 1 : 2
Ratio of number of days { 1/3 : 1/1 : 1/2 }
or 2 : 6 : 3
Hence, (a) is correct [ Time = 1/ Efficiency ]
Efficiency of A + B = 100/(20/3) = 15%
No. of days ( A:B ) = 4 : 5
Efficiency ( A:B ) = 5 : 4
? Efficiency of B = (4/9) x 15 = 20/3 = 62/3%
Efficiency of A + B = 33.33% = 100/3
Ratio of efficiency of A and B = 3 : 1
? Efficiency of A = (3/4) x 33.33 = 25%
? Number of days taken by A = 100/25 = 4
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