April 18th, 2014, 06:39 PM |
#1 |

Newbie Joined: Apr 2014 From: San Diego Posts: 1 Thanks: 0 | Need Help.
Some hardly hikers start on a walk at 2:00 PM and return at 8:00 PM. Their speed is 4 miles per hour on level land, 3 miles per hour uphill, and 6 miles per hour downhill. How many miles was their hike? a) 24 b) 26 c) 28 d) 36 |

April 18th, 2014, 10:30 PM |
#2 |

Newbie Joined: Aug 2011 Posts: 17 Thanks: 1 |
Not sure why this is i the Calculus forum - it is just Distance = Rate times Time. D = RT, so T= D/R. Let A = distance along level round on outgoing portion of the hike the time for this part of the hike = A/4 B = uphill distance of outgoing portion and time = B/6 C = downhill distance of outgoing portion and time = C/3 So A also = distance along level round on outgoing portion of the hike time again = A/4 B = downhill distance of outgoing portion, time = B/3 C = uphill distance of outgoing portion, time = C/6 Adding up total time: A/4 + B/6 + C/3 + A/4 + B/3 + C/6 = (A+B+C)/2 = 6 hours. So A+B+C = 12 and the total distance is 2(A+B+C) = 24 miles. |

April 18th, 2014, 10:54 PM |
#3 |

Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 520 Math Focus: Calculus/ODEs | |

April 20th, 2014, 09:15 PM |
#4 | |

Newbie Joined: Aug 2011 Posts: 17 Thanks: 1 | Quote:
| |