J's answer to Michelle's Primary 6 Maths Speed Singapore question.
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When Ham travelled ⅓ of the race, Tony was 15km ahead of him.
15km ÷ 90km/h = 1/6 h = 10min
Tony took 10 min to travel this 15km from the ⅓ mark. This tells you that he actually reached the mark 10 min before Ham.
What this means is for every ⅓ of the race Ham is 10min slower than Tony. He will take 10 min more to finish for every ⅓ of the race.
So for the next ⅓, he would be another 10min slower than Tony than he already was at ⅓ of the race. And for the last ⅓, Ham will yet again be another 10min slower than he already was at ⅔ of the race.
So for the whole race, Ham would be 3 x 10min = 30min slower than Tony
Time Ham reached would be 0935 + 0035 = 1005, which is 10.05am
15km ÷ 90km/h = 1/6 h = 10min
Tony took 10 min to travel this 15km from the ⅓ mark. This tells you that he actually reached the mark 10 min before Ham.
What this means is for every ⅓ of the race Ham is 10min slower than Tony. He will take 10 min more to finish for every ⅓ of the race.
So for the next ⅓, he would be another 10min slower than Tony than he already was at ⅓ of the race. And for the last ⅓, Ham will yet again be another 10min slower than he already was at ⅔ of the race.
So for the whole race, Ham would be 3 x 10min = 30min slower than Tony
Time Ham reached would be 0935 + 0035 = 1005, which is 10.05am
Date Posted:
4 years ago
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