
By: fanny6573 (offline) Sunday, August 10 2014 @ 05:28 AM CDT (Read 1390 times)



fanny6573 
Hi please help on the question below:
Jean started his journey from town x to y at a constant speed. Sometime later, Michelle started her journey from town x to town y at the same speed as jean.
At 11 a.m, Jean travelled 4 times the distance. Michelle had travelled.
At 11.42 a.m, Jean finished the journey while Michelle travelled half of the distance from town x to town y.
At what time did Jean start his journey?
Thank you.
Regards
Fanny

Junior
Registered: 07/19/10 Posts: 28





By: echeewh (offline) Sunday, August 10 2014 @ 10:37 PM CDT



echeewh 
Hello <fanny6573>
Following is my worked solution :
***  for alignment purpose
********************** <11am> * <11.42am>
J 
M 
******* <11am> * <11.42am>
By 11am,
J completed 4u distance ; M completed 1u of same distance.
By 11.42am,
J completed the entire distance; M completed half the distance.
From above models and given that both J, M speeds are same and constant,
Time taken by M to complete half distance
= 1u (distance) + 42 mins
Referring to J's model,
Time taken by J to complete full distance
= 4u (distance) + 42 mins
Since both speeds are same and constant,
J would also take [ 1u (distance) + 42 mins ] to complete half distance.
This infers the following :
J would need [ 1u (distance) + 42 mins ] to complete the 3u (distance)
i.e. J would take 42 mins to cover 2u (distance)
Hence, 1u (distance) > 42 ÷ 2 = 21 mins
4u (distance) > 4 × 21 = 84 mins = 1 hr 24 mins
Time (when J started journey):
1 hr 24 mins before 11am
= 11 00  1 24
= 9 36
J started journey at 9.36am
==========
Trust this helps.
Do let me know again if this is different from your <Answerkey> or if there's further clarification.
Cheers,
Edward.

Active Member
Registered: 04/21/11 Posts: 627





By: fanny6573 (offline) Monday, August 11 2014 @ 12:31 AM CDT



fanny6573 

Junior
Registered: 07/19/10 Posts: 28



