Jack's answer to Crystal Ang's Primary 6 Maths Speed Singapore question.
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Add both of their speed and divide the distance, you will get the amount of time they need to meet.
Date Posted:
4 years ago
Can i know why do we need to add 2 of their speed
Let use this example to explain.
Given:
Laura 81km/h
Mandy 94 km/h
Total distance=140km.
Assumed they travelled 1 hour, total distance travelled: 81+94 = 175km.
175km ->1hour
140km -> 1/175 × 140 = 3/4 hr
Given:
Laura 81km/h
Mandy 94 km/h
Total distance=140km.
Assumed they travelled 1 hour, total distance travelled: 81+94 = 175km.
175km ->1hour
140km -> 1/175 × 140 = 3/4 hr
So added their distance to know what is the distance travelled by them in 1 hour.
After knowing they travelled 175km in 1 hour, I just used comparison/unit to find the time for 140km.
After knowing they travelled 175km in 1 hour, I just used comparison/unit to find the time for 140km.
It's like if 3apples is $15, how much is 2 apple?
3apples->$15
2apples->15/3 x 2 = $10
3apples->$15
2apples->15/3 x 2 = $10
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