Latest self Aptitude Question SOLUTION: A and B can finish a piece of work in 20 days .B and C in 30 days and C and A in 40 days. In how many days will A alone finish the job (a) 48 (b) 34 2/7 (c) 44 (d) 48

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(#M40011787) SELF question Keep an EYE

A and B can finish a piece of work in 20 days .B and C in 30 days and C and A in 40 days. In how many days will A alone finish the job
(a) 48
(b) 34 2/7
(c) 44
(d) 48

dhanalakshmi (11 years ago)

Unsolved Read Solution (8)

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Garima  (11 years ago)

A and B can finish a piece of work in 20 days .B and C in 30 days and C and A in 40 days.
2*(A+B+C)'s one day work = 1/20 + 1/30 +1/40 = 13/120 work
(A+B+C)'s one day work = 13/240 work
A's one day work = 13/240 - 1/30 = 5/240 = 1/48

so A alone can complete work in 48 days.

Is this solution Helpfull? Yes (5) | No (2)  

Anurag  (11 years ago)

1/a+1/b=1/20......(1)
1/b+1/c=1/30.......(2)
1/c+1/a=1/40...(3)
Adding (1) and (3) and subtracting (2) we get 2*(1/a)=5/120
so 1/a=5/240
so a=48 days

Is this solution Helpfull? Yes (3) | No (2)  

Devendra Marghade  (11 years ago)

Ans 48 days
(A+B) 1 day=1/20 ,(B+C) 1 day=1/30, (C+A) 1 day=1/40
(A+B)-(B+C)=(A-C)=1/20 - 1/30=1/60
Now (A-C)+(C+A)=2A=1/60 +1/40= 1/24
Therefore A's 1 day work=1/(2*24)=1/48
So A can complete the work in 1/(1/48)=48 days

Is this solution Helpfull? Yes (2) | No (1)  

Harsh Pandya  (8 years ago)

( A+B )+(B+C)+(C+A) = (1/20) + (1/30) + (1/40)

2(A+B+C) = 13/120

(A+B+C) = (13/240)
A's work is

(A+B+C) - (B+C) = (13/240) - (1/30) = 1/48


SO 48 days...

Is this solution Helpfull? Yes (1) | No   

thangamari  (11 years ago)

ans is 48
gn:
per day work of each
A+B=1/20
B+C=1/30
A+C=1/40
by solving above 3 eqns
we get
A=5/240
=>In days we consider 240/5=48

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madhavaram mahendra  (11 years ago)

a+b 1 day work is 1/20,b+c=1/30,(c+a)=1/40
2(a+b+c) 1 day work is 1/20+1/30+1/40
so a+b+c 1 day work is 13/240
a 1 day work is (a+b+c)-(b+c)=13/240-1/30
1/48
so a can finish in 48 days

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Disha  (6 years ago)

Let 120 unit be the total work.Then in one day,
A+B=6 unit
B+c=4 unit
A+C=3 unit
Solving this ...We get,
A=2.5 unit in 1 day
Hence 120 unit in 48 days.

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Vivek kumar  (5 years ago)

A+B=20 days
B+C=30 days
C+A=40 days
Take out LCM of above three i.e., LCM of 20,30and 40 which will be 120(and this will be total work).
Therefore, A+B= 6 work/day....(1)
B+C= 4 work/day....(2)
C+A= 3 work/day....(3)
Adding all of the above three equations we get A+B+C= 13/2....(4)
From equation 2 and 4, we get A=5/2.
Therefore eff.=work/time
120*2/5=48 days

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