This blog is managed by Song Hock Chye, author of Improve Your Thinking Skills in Maths (P1-P3 series), which is published and distributed by EPH.

Monday, July 19, 2010

ACS Primary 2009 PSLE Math Prelim Paper 2 Q14

At 9.30 am, Mr Yeo left Town A for Town B driving at a speed of 75 km/h throughout his journey. At 10.30 am, Mr Lee also left Town A for Town B driving at a certain speed. He kept to the same speed throughout his journey. At 1.30 pm, both of them passed a Shopping Mall that was 150 km way from Town B. How many minutes earlier did Mr Lee reach Town B than Mr Yeo?


(Town A to Shopping Mall)
Yeo --> distance = 75 km/h x 4h = 300 km
Lee ---> speed = 300 km divided by 3h = 100 kmh

(Shopping Mall to Town B)
Lee --> time = 150 km divided by 100 km/h = 1.5 h
Yeo --> time = 150 km divided by 75 km/h = 2 h

2 h - 1.5 h
= 0.5 h
= 30 min

Answer: 30 minutes

1 comment:

Anonymous said...

There is a mistake in the diagram. It should be Lee, not Lim.