### Discussion :: Boats and Streams - Data Sufficiency 2 (Q.No.1)

Each of the questions given below consists of a question followed by three statements. You have to study the question and the statements and decide which of the statement(s) is/are necessary to answer the question.

Tarandeep said: (Nov 26, 2012) | |

How this formula for Avg Speed is calculated? |

Amit said: (Nov 9, 2013) | |

Avg. speed = Total distance / Total time = 2L / t1 + t2. Time = distance / speed so, t1 = L / x and t2 = L / y. t1 + t2 = L(x+y) / xy. Total time = L(x+y) / xy. Total distance = 2L. Avg. speed = 2xy/x+y. |

Aman said: (Dec 3, 2013) | |

Can anybody tell me how we get the value 4 in that average speed formula you have putted. |

Aashit said: (Jun 25, 2014) | |

Why has 4 been substituted for 'x' when 4=x+y? |

Rahul said: (Feb 15, 2015) | |

x is the speed of the boat upstream, and y is the speed of the boat downstream. |

Swarnashree said: (Aug 28, 2015) | |

Why x is taken as speed of the boat upstream? |

Shashi said: (Oct 22, 2016) | |

How is statement 3 related to question? There is no need of 3rd statement or no relation b/w 3rd to another statement. |

Harshavardan said: (Jan 10, 2017) | |

My Analysis. Upstream is 4kmps and downstream is 12kmps. Boat speed still in water =(down stream+upstream)/2 = (1/2) * (12+4) = 8kmps. Boat speed against the water =(down stream-upstream)/2 = (1/2) * (12-4) = 4kmps. So, Statments 1&2 are efficient to get this answer. Answer is Option "A". |

Priya said: (May 6, 2018) | |

123+45=168, 168*0=0, Therefore the answer is 0. But unfortunately, the answer is not 0. Because any answer cannot be 0. So, we increment the answer by 1 to avoid any problems. Therefore the answer is 1. |

Abhilasha said: (Jul 17, 2018) | |

3rd statement itself is enough as [(u+v)+(u-v)]/2=6. Which gives u = 6; where u is the speed of the boat in still water and v is the speed of the stream. |

Kapadiya Sagar said: (Jun 26, 2020) | |

Options 1 and 3 become same. a+b = 6kmph. So with one equation two unknown is not solvable. So, the Correct option is [A]. |

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