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aamir and birju can cut 5000 g of wood in 20 min.birju and charles can cut 5000 g of wood in 40 min.charles and aamir can cut 5 kg of wood in 30 min.how much time charles will take to cut 5 kg wood alone??
edited | 217 views

I think i should be 240 min

let CA capacity of Amir, CB capacity of Birju, CC capacity of Charles.

now Capacity=Work/Time

then form the question we can write

CA+CB=5000/20=500/2   => 2CA+2CB=500...............1

CB+CC=5000/40=250/2   => 2CB+2CC=250.................2

CC+CA=5000/30=500/3   => 3CC+3CA=500.................3

Now Solving the equation 1,2,3 for CC(As we need to answer about charles) we get CC=125 / 6

Again CC=work to be done by charles/Time take to do the work (t)

125/6=5000/t

t  =  (5000*6)/125

= 240 Min

hope it helps
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+1 vote
Let capacity of each person to cut 5000 g of wood be,

AAMIR-  A;

BIRJU - B;

CHARLES - C;

given : A+B=1/20 ; B+C=1/40 ; C+A=1/30 ;

solving the above 3 equations with 3 unknown variables we get :C=1/240

=> CHARLES takes 240 min
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