
Algebra PreAlgebra and Basic Algebra Math Forum 
 LinkBack  Thread Tools  Display Modes 
July 17th, 2014, 02:58 AM  #1 
Senior Member Joined: Jan 2012 Posts: 724 Thanks: 7  Find the normal average rate at which Isatu walks to school.
Isatu walks a distance of 1.5km to school everyday; her rate of walking being always constant. On a certain day, owing to ill health, she had to reduce her walking rate by 0.5km/ h and as a result, she took extra 6 minutes to reach the school than usual. Find the normal average rate at which Isatu walks to school. Time t = 6/60=1/10h Let her normal walking rate be x. If she reduce it by 0.5km/h, the walking rate becomes (x0.5)km/h when she was sick. I can't go further here, I need help please. 
July 17th, 2014, 05:27 AM  #2 
Senior Member Joined: Nov 2013 From: Baku Posts: 502 Thanks: 56 Math Focus: Geometry 
Velocity is v, time is t. vt=1.5 and (v0.5)(t+0.1)=1.5 6 min. is 0.1 hours. We get t=(v0.5)/5 and we know t=1.5/v. Rest is easy. Change your profile picture. 
July 17th, 2014, 08:21 AM  #3 
Senior Member Joined: Apr 2014 From: Europa Posts: 571 Thanks: 176 
You forgot change your profile picture. $\displaystyle \color{blue}{Read \ "Decalogue"... \\\;\\ and\ let \ you \ read .}$ 
July 17th, 2014, 11:20 AM  #4  
Senior Member Joined: Jan 2012 Posts: 724 Thanks: 7  Quote:
 
July 17th, 2014, 09:27 PM  #5 
Senior Member Joined: Jan 2012 Posts: 724 Thanks: 7  
July 18th, 2014, 12:41 AM  #6 
Senior Member Joined: Apr 2014 From: Europa Posts: 571 Thanks: 176  
July 18th, 2014, 06:23 AM  #7 
Senior Member Joined: Nov 2013 From: Baku Posts: 502 Thanks: 56 Math Focus: Geometry 
(v0.5)(t+0.1)=1.5 therefor vt+0.1v0.5t0.05=1.5 and we know vt=1.5 therefore 0.1vo.5t0.05=0 therefore v5t0.5=0 and t=1.5/v therefore v7.5/v0.5=0 v^2  0.5v  7.5 = 0 
July 19th, 2014, 09:00 PM  #8  
Senior Member Joined: Jan 2012 Posts: 724 Thanks: 7  Quote:
Using quadratic formula, we will come to a point where we have $\displaystyle \frac{0.5\pm\sqrt{30.25}}{2}$ = $\displaystyle \frac{0.5pm5.5}{2}\rightarrow \\ v=3 \;or 2.5$ So normal rate = $3km/h$ Last edited by Chikis; July 19th, 2014 at 09:19 PM.  
July 19th, 2014, 09:15 PM  #9 
Senior Member Joined: Nov 2013 From: Baku Posts: 502 Thanks: 56 Math Focus: Geometry 
2.5 is also valid solution, if Isatu walks backwards.

July 19th, 2014, 10:22 PM  #10 
Math Team Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 13,133 Thanks: 914  

Tags 
average, find, isatu, normal, rate, school, walks 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
How to find the average rate of change  Shayna  Calculus  1  June 4th, 2014 05:51 PM 
Average Rate of Change  headsupman  Algebra  1  February 6th, 2013 02:59 PM 
Average Rate of Change  ChristinaScience  Calculus  2  October 19th, 2011 11:45 PM 
Average Rate of Change Between Points  ChristinaScience  Calculus  6  October 19th, 2011 11:21 PM 
Average Rate of Change  symmetry  Algebra  6  June 12th, 2007 01:53 PM 