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Important Formulas

Vedic/Quicker Math

Alligation or Mixture

Area

Average

Banker's Discount

Boats and Streams

Calendar

Chain Rule

Clock

Compound Interest

Decimal Fraction

Height and Distance

Logarithm

Numbers

Odd Man Out and Series

Partnership

Percentage

Permutation & Combination

Probability

Problems on Ages

Problems on H.C.F & L.C.M

Problems on Numbers

Problems on Trains

Profit & Loss

Races and Games

Ratio and Proportion

Simple Interest

Simplification

Square Root and Cube Root

Stocks and Shares

Surds and Indices

Time and Distance

Time and Work

True Discount

Volume and Surface Area

Practice Questions

:- You can add tough questions into
your favourite list for second revision. Note |

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
Explanation:-
Answer : DDiscuss it below :Part filled in 4 minutes = 4
^{1}/_{15}^{1}/_{20}^{7}/_{15}^{7}/_{15}^{8}/_{15}^{1}/_{20}^{1}/_{20}^{8}/_{15}^{8}/_{15}^{2}/_{3}= 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
Explanation:-
Answer : CDiscuss it below :Let the slower pipe alone fill the tank in x minutes.Then, faster pipe will fill it in ^{x}/_{3}_{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
Explanation:-
Answer : CDiscuss it below :Suppose pipe A alone takes x hours to fill the tank.Then, pipes B and C will take ^{x}/_{2}^{x}/_{4}_{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
Explanation:-
Answer : CDiscuss it below :Part filled by (A + B + C) in 1 hour_{ = } ^{ 1 }_{ + } ^{ 1 } _{ + } ^{ 1 }_{ = } ^{ 1 }^{72} ^{120} ^{90} ^{90}
= ^{1}/_{3}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
Explanation:-
Answer : ADiscuss it below :Part filled by A in 1 min. = ^{1}/_{20}^{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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