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**Answer :-**

*1. (b) (Total capacity)*

*60*

*Efficiency 3 2*

*Hour → 20 30*

*(A) (B)*

*filling pipe*

*According to questions,*

*Pipe ‘A’ is closed after some time.*

*And Tank is filled in 18 minutes so*

*B started filling in beginning and*

*Worked till last i.e. 18 minutes*

*So, 2×18 = 36 units is filled*

*Work left = 60 – 36 = 24 units*

*This 24 units must be filled by Pipe*

*A in beginning.*

*It can fill it in*

*= 8 minutes*

*2. (d)*

*Efficiency*

*Hours →*

*(filling) (emptying)*

*Total efficiency of both pipes is*

*Tank will be filled in*

*3. (c) Apply formula of*

*Let ‘P’ pumps are required to empty the*

*Reservoir.*

*P = 10 pumps*

*4. (a) Pipe A : Pipe A-leakage*

*Efficiency → 2 : 1*

*Time 1 : 2*

*×36 1 unit = 36 hrs*

*36 hrs*

*5. (d) let (A+B) fills 1 liter in 1 minutes*

*Then (A+B) fills in 36 minutes = 36 liters*

*According to question*

*(A+B) work only 30 minutes then pipe filled by*

*(A+B) in 30 minutes is = 30 liters*

*Remaining part = 6 liters*

*6 liters part filled by A in = 10 minutes*

*1 part filled by A =*

*minutes*

*36 part filled by A =*

*= 60 minutes*

*A + B = 36 minutes*

*A = 60 minutes*

*(T.W)*

*180*

*Efficiency 3 5 liters/minute*

*60 36*

*(A) (A+B)*

*A’s efficiency = 3 liters/minutes*

*B’s efficiency = 2 liters/minutes.*

*B can alone fill the tank in*

*=*

*= 90 minutes*

*6. (c) (Total capacity)*

*120*

*Efficiency → 6 5 8*

*Hours → 20 24 15*

*(A) (B) (A+B+C)*

*(A+B+C) one day work = 8*

*6+5–C = 8*

*11–C = 8*

*C = 3*

*C = 3 units T.C = 120*

*×1 ×1*

*Actual 3 Galons 120 units*

*emptying*

*capacity*

*= 120 galons*

*7. (d)*

*120*

*Efficiency → 30 15 10 –12*

*Hours → 4 8 12 10*

*(P) (Q) (R) (S)*

*In order to fill the cistern in less time.*

*So, efficiency of filling should be more*

*Now, check all options*

*(A) → Q efficiency 15 units/hr*

*(B) → (P + R – S) efficiency*

*= 30+10–12 = 28 units/hr*

*(C) → (P + S) efficiency = 30 – 12*

*= 18 units/hr*

*(D) → (P + Q – S) efficiency*

*= 30+15–12 = 33 units/hr*

*Option ‘D’ is answer.*

*Since efficiency of option ‘D’ is highest.*

*8. (d) (Total capacity)*

*30*

*Efficiency→ 3 2*

*Hours → 10 15*

*(–A) (–A+B)*

*Emptying Filling*

*Pipe A is emptying at 3 units/hr*

*When filling pipe ‘B’ start function*

*then emptying rate comes down to*

*2 units/hr*

*So, filling pipe efficiency is*

*(3–2) = 1 unit/hr*

*Pipe ‘B’ will fill tank in =*

*= 30 hrs*

*Filling rate is 4 liters/minutes*

*It will fill 4×60 = 240 liters/hr.*

*Total capacity = 240×30 = 7200 liters*

*9. (c) (Total capacity)*

*12*

*Efficiency→ 3 2*

*Hours → 4 6*

*(A) (B)*

*A will fill 3 units of water in Ist hour*

*B will fill 2 units of water in IInd hours*

*5 units in 2 hours*

*5 units is filled in 2 hours*

*×2 ×2*

*10 units 4 hours*

*Work left = 12–10 = 2 units*

*Now, A will begin he completes 2*

*Units in*

*hours*

*Total time = 4*

*hours*

*10. (c) Qty Time(in minutes)*

*Boy → 4 liters 3*

*Girl→ 3 liters 4*

*Boy → (4 3)×4 = 16 liters*

*In 12 minutes*

*Girl→ (3 4)×3 = 9 liters*

*In 12 minutes*

*(Boy + Girl) pour*

*25 liters 12 minutes*

*×4 ×4*

*100 liters 48 minutes*