Online Course Discussion Forum

Math Challenge 1B Summer 9.24 and 9.27

 
 
Picture of Han Li
Math Challenge 1B Summer 9.24 and 9.27
by Han Li - Monday, 14 August 2023, 6:46 PM
 

Can someone please guide me or give me hints on 9.24 and 9.27? I might have the correct equations, but does not match the answer on the website, so I don't know what I'm doing wrong.

 
Picture of Dr. Kevin Wang
Re: Math Challenge 1B Summer 9.24 and 9.27
by Dr. Kevin Wang - Tuesday, 15 August 2023, 2:25 AM
 

It appears that both of these questions have some errors that could lead to confusion.  Sorry about that.  Here are some explanations.

9.24: The question should mention that Derrick and Jimmy meet at some place along the route.  When they meet, their combined travel time is $41$ hours.  (If we don't mention that they meet, and both travel the full distance between NY and LA, then the fact that Derrick starting off 2 hours later than Jimmy will not make sense, since it doesn't affect the total time.)

9.27: The posted answer key is incorrect.  The actual answer should be "approximately $6.63$ m/s".  If you got this answer, then good job!  If not, please show how you did it, and we will see whether it can be corrected.