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 By: geniuskids (offline)  Sunday, August 18 2013 @ 02:46 AM CDT (Read 1459 times)
geniuskids

Hi there,

Really need someone to solve this question:-

(Q3) Eric and Collin started travelling from Town X to Town Y at the same time.
Eric travelled at an average speed that was 15km/h more than Collin's average speed.
By the time Eric reached the midpoint between Town X and Town Y, Collin was 500m behind him.
How long did Eric take to travel from Town X to Town Y?

Answer: 4 min

Active Member

Registered: 11/12/11
Posts: 169

 By: echeewh (offline)  Sunday, August 18 2013 @ 06:31 AM CDT
echeewh

Hey <geniuskids>,

Following is my worked solution:

*** - for alignment purpose

X ****************************** Y
|--------------------|--------------------|
|-> ************ |->
E ************* E1
|-> ****** |->
C ******* C1

d(C1E1) = 500 m = 0.5 km
t(CC1) = t(EE1)
s(E) = s(C) + 15

Given that C was 500m (0.5 km) behind E (at C1) by the time E reached the midpoint (E1),

this infers that E travelled an extra distance of 0.5 km given E's extra speed of 15 km/h.

Hence,
t(EE1) = extra distance ÷ extra speed
= 0.5 ÷ 15
= (1/30) hr

Time taken for E to travel from X to Y = t(EY)
= 2 × (1/30)
= (1/15) hr
= 4 mins

=========

Trust this helps.

Do let me know again if there's further clarification.

Cheers,
Edward

Active Member

Registered: 04/21/11
Posts: 627

 By: geniuskids (offline)  Monday, August 19 2013 @ 04:13 AM CDT
geniuskids

Hi Edward,

Thank you for your help! Got it!

Active Member

Registered: 11/12/11
Posts: 169

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