My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum


Reply
 
LinkBack Thread Tools Display Modes
April 18th, 2014, 05:39 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
ConnieLam is offline  
 
April 18th, 2014, 09:30 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.
alstat is offline  
April 18th, 2014, 09:54 PM   #3
Senior Member
 
MarkFL's Avatar
 
Joined: Jul 2010
From: St. Augustine, FL., U.S.A.'s oldest city

Posts: 12,211
Thanks: 520

Math Focus: Calculus/ODEs
Quote:
Originally Posted by alstat View Post
Not sure why this is i the Calculus forum...
I have moved the thread appropriately.
MarkFL is offline  
April 20th, 2014, 08:15 PM   #4
Newbie
 
Joined: Aug 2011

Posts: 17
Thanks: 1

Quote:
Originally Posted by alstat View Post
Not sure why this is in 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 incoming portion of the hike
time again = A/4
B = downhill distance of incoming portion, time = B/3
C = uphill distance of incoming 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.
Just fixing some typos!
alstat is offline  
Reply

  My Math Forum > High School Math Forum > Algebra



Thread Tools
Display Modes






Copyright © 2019 My Math Forum. All rights reserved.