# Sarin’s family took a train part 7 (Math Question)

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The blog postings are about the Singapore Math. The readers can learn from the postings about Solving Singapore Primary School Mathematics. The blog presenting the Math Concept, Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids will learn how to deal with Math Modeling, Problem Sum from Lower Primary School to Upper Primary School level. This posting is an upper primary school math question on Speed.

Read the posting on Sarin’s family took a train about Sarin’s family had their train ride from Singapore Tanjong Pagar Train Station.

Read also the posting on Sarin learns rate of change in school (Math Concept) to learn about concept of Speed and Distance.

Upper primary school mathematics question UPQ228

At 6 a.m., Train KTM15 left Singapore Woodlands Station for Malaysia Kluang Station at a speed of 65 km/h. At the same time, another Train KTM81 left Malaysia Kluang Station for Singapore Woodlands Station at a speed of 55 km/h. The distance between the two towns was 720 km. At what time did the 2 trains pass each other?

Solution:

The trains moving toward each other with different speeds

When they pass each other, the time travelled are the same = t

The distance travelled by KTM15 = 65t

The distance travelled by KTM81 = 55t

The total distance = 720km

65t + 55t = 120t = 720km

t = 720 ÷ 120 = 6 h

The trains pass each other at 12 noon

Alternative solution:

The relative speed of the trains = 65 + 55 = 120 km/h

The number of hour for both trains to travel 720 km = 720 ÷ 120 = 6 h

The trains pass each other at 12 noon