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Q1.	Two pipes A and B can fill a tank in 15 minutes and 20 minutes respectively. Both the pipes are opened together but after 4 minutes, pipe A is turned off. What is the total time required to fill the tank ?
A.	10 min 20 sec [Wrong Answer]
B.	11 min 45 sec [Wrong Answer]
C.	12 min 30 sec [Wrong Answer]
D.	14 min 40 sec [Correct Answer]
View Answer 2 -5 Explanation:- Answer : D Discuss it below : Part filled in 4 minutes = 4 ( ¹/₁₅ + ¹/₂₀ ) = ⁷/₁₅ Remaining part = (1 - ⁷/₁₅ ) = ⁸/₁₅ Part filled by B in 1 minute = ¹/₂₀ ¹/₂₀ : ⁸/₁₅ :: 1 : x Or x = ( ⁸/₁₅ X 1 X 20 ) = 10 ²/₃ = 10 min. 40 sec. So The tank will be full in (4 min. + 10 min. 40 sec) = 14 min. 40 sec. Click here for more comments


Q2.	One pipe can fill a tank three times as fast as another pipe. If together the two pipes can fill the tank in 36 minutes, then the slower pipe alone will be able to fill the tank in :
A.	81 min [Wrong Answer]
B.	108 min [Wrong Answer]
C.	144 min [Correct Answer]
D.	192 min [Wrong Answer]
View Answer 1 -1 Explanation:- Answer : C Discuss it below : Let the slower pipe alone fill the tank in x minutes. Then, faster pipe will fill it in ^x/₃ minutes. _{So =} ¹ ₊ ³₌ ¹ ^x ^x ³⁶ _⇔ ⁴ ₌ ¹ ^x ³⁶ So x = 144 min. Click here for more comments


Q3.	A tank is filled in 5 hours by three pipes A, B and C. The pipe C is twice as fast as B and B is twice as fast as A. How much time will pipe A alone take to fill the tank ?
A.	20 hrs [Wrong Answer]
B.	25 hrs [Wrong Answer]
C.	35 hrs [Correct Answer]
D.	Cannot be determined [Wrong Answer]
View Answer 1 -2 Explanation:- Answer : C Discuss it below : Suppose pipe A alone takes x hours to fill the tank. Then, pipes B and C will take ^x/₂ and ^x/₄ hours respectively to fill the tank. _{So =} ¹ ₊ ² ₊ ⁴ ₌ ¹ ^x ^x ^x ⁵ ⁷ ₌ ¹ ^x ⁵ x = 35 hrs. Click here for more comments


Q4.	Pipe A can fill a tank in 5 hours, pipe B in 10 hours and pipe C in 30 hours. If all the pipes are open, in how many hours will the tank be filled ?
A.	2 [Wrong Answer]
B.	2.5 [Wrong Answer]
C.	3 [Correct Answer]
D.	3.5 [Wrong Answer]
View Answer 1 -2 Explanation:- Answer : C Discuss it below : Part filled by (A + B + C) in 1 hour ₌ ¹ ₊ ¹ ₊ ¹ ₌ ¹ ⁷² ¹²⁰ ⁹⁰ ⁹⁰ = ¹/₃ So All the three pipes together will fill the tank in 3 hours. Click here for more comments


Q5.	Two pipes A and B can fill a tank in 20 and 30 minutes respectively. If both the pipes are used together, then how long will it take to fill the tank ?
A.	12 min [Correct Answer]
B.	15 min [Wrong Answer]
C.	25 min [Wrong Answer]
D.	50 min [Wrong Answer]
View Answer 1 -1 Explanation:- Answer : A Discuss it below : Part filled by A in 1 min. = ¹/₂₀; Part filled by B in 1 min. = ¹/₃₀ Part filled by (A + B) in 1 min : ₌ ¹ ₊ ¹₌ ¹ ²⁰ ³⁰ ¹² So Both the pipes can fill the tank in 12 minutes. Click here for more comments

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