Question:
Town P was exactly halfway between Town M and Town N. At 08 00, Nancy started travelling from Town M to Town N while Seo Joon started travelling trom Town N to Town M. Nancy travelled at 50 m/min while Seo Joon travelled at 80 m/min. They did not change their speeds throughout the journey. When they passed each other, their distance from Town P was 120 m. At what time did Seo Joon reach Town M?
Solution:
![P6 / Red Swastika / 2020 / SA2 Prelims / Paper 2 – Q04 [2 marks]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2020/11/P6_Red_Swastika_2020_SA2_Paper2_Q04-Qns.jpg?resize=400%2C260&ssl=1)
![P6 / ACS / 2018 / SA1 / Paper 1 – Q17 [1 mark]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2021/04/P6_SA1_2018_ACS_Paper1_Q17-Qns.jpg?resize=400%2C232&ssl=1)
Hi,
I cannot understand why the diff (Dist) is 120 x 2? Appreciate if you can help me see the logic behind it. Thank you.
Hi Jo’s mum!
We are trying to find the difference in the distance travelled by Nancy and Seo Joon.
Imagine if both Nancy and Seo Joon starts from the RIGHT (Town N) and travelled towards the LEFT (Town M), then Nancy would have stopped 120 metres on the RIGHT of Town P, and Seo Joon would have stopped 120 metres on the LEFT of Town P. Therefore, Seo Joon would have travelled 120m x 2 = 240m more than Nancy.
This explanation is also mentioned in the Youtube video here at 1m25s (https://www.youtube.com/watch?v=z4WtnXhS1tA#t=1m25s).
Hope this helps!
Let me know if you need further clarification =)