Question

20. (1) Let ( A ) takes ( n ) days to complete a work then, time taken by ( B=2 n ) ( (A+B)^{prime} 1 ) day work ( =frac{1}{12} )
( Rightarrow quad frac{1}{n}+frac{1}{2 n}=frac{1}{12} )
( Rightarrow quad frac{2+1}{2 n}=frac{1}{12} )
( Rightarrow quad n=frac{12 times 3}{2}=18 )
( therefore ) Time taken by ( B ) alone ( =2 n=2 times 18 )
( =36 ) days

# 20. A and B can do a job together in 12 days. A is 2 times as efficient as B. In how many days can B alone complete the work (1) 36 (2) 12 (3) 18 (4) 9

Solution