
Algebra PreAlgebra and Basic Algebra Math Forum 
 LinkBack  Thread Tools  Display Modes 
July 9th, 2017, 07:17 PM  #1 
Newbie Joined: Jun 2017 From: North Texas Posts: 19 Thanks: 1  Help with a KA problem (Slope,speed, rate) 
July 9th, 2017, 08:09 PM  #2 
Senior Member Joined: May 2016 From: USA Posts: 1,029 Thanks: 420 
Because she did not start right away. She rode at a constant speed once she finished getting ready, but that means that her average speed was not constant from the time she got the call. It was only constant once she started pedaling. She could travel 5 km in 40 minutes after the call, giving an average rate of 0.125 km / min from the time of the call. She could travel 7 km in 52 minutes after the call, giving an average rate of about 0.135 km /min from the time of the call. So let's set it up as a system of equations. $\text {c = time spent cycling}.$ $\text {g = time spent getting ready}.$ $\text {t = total time}.$ $\text {r = constant speed while cycling}.$ $\text {d = distance traveled}.$ $\therefore d = 0 * g + c * r = cr$ because no distance is traveled during g. $\text {And } t = c + g \implies g = (t  c) \implies d = cr = (t  g)r = tr  gr.$ $7 = 52r  gr.$ $5 = 40r  gr.$ $\therefore 7  5 = (52r  gr)  (40r  gr) \implies 2 = 12r.$ What does that mean? It means she pedals 2 kilometers in 12 minutes. So how long does it take her to pedal 1 kilometer? 
July 9th, 2017, 11:17 PM  #3 
Newbie Joined: Jun 2017 From: North Texas Posts: 19 Thanks: 1 
Triple dots = therefore and arrows means implies? right? I quoted your post to see but still getting the symbols down. 
July 10th, 2017, 12:03 AM  #4 
Senior Member Joined: Feb 2016 From: Australia Posts: 1,591 Thanks: 546 Math Focus: Yet to find out.  

Tags 
problem, rate, slope, speed 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Find the ratio of his usual speed to his speed that day.  Chikis  Elementary Math  25  January 31st, 2014 08:48 AM 
Slope acceleration problem  eddybob123  Physics  1  September 30th, 2013 06:40 PM 
Choosing correct deceleration rate to get zero speed  MikeMJ  Computer Science  3  June 26th, 2012 10:00 AM 
Speed problem  alikn  Physics  3  October 30th, 2009 03:53 PM 
Polar slope/rate  Kaitosan  Calculus  0  April 27th, 2009 01:23 PM 