Daryl Yong's answer to cheesyeggs's Secondary 1 Maths Singapore question.
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(a)
All 3 drivers meet again at the lowest common denominator of the 3 trip intervals.
LCD(30,18,25) = 450
To get the above result, first do prime factorisation of all the trip intervals:
30 = 2 x 3 x 5
18 = 2 x 3^2
25 = 5^2
The lowest common denominator will be the product of the highest power of each prime factor that appears:
2 x 3^2 x 5^2 = 450
Now, 450 mins = 7 hours 30 mins
Hence, all 3 drivers meet again at 0600 hrs + 0730 hrs = 1330 hrs (1:30pm)
(b)
Earnings = $9 x 2 x 12 x 6 x 4 = $5184
Costs = $2000 + $150 + ($70 x 6 x 4) = $3830
Yes, Mr Lim will be able to cover his costs from his earnings
All 3 drivers meet again at the lowest common denominator of the 3 trip intervals.
LCD(30,18,25) = 450
To get the above result, first do prime factorisation of all the trip intervals:
30 = 2 x 3 x 5
18 = 2 x 3^2
25 = 5^2
The lowest common denominator will be the product of the highest power of each prime factor that appears:
2 x 3^2 x 5^2 = 450
Now, 450 mins = 7 hours 30 mins
Hence, all 3 drivers meet again at 0600 hrs + 0730 hrs = 1330 hrs (1:30pm)
(b)
Earnings = $9 x 2 x 12 x 6 x 4 = $5184
Costs = $2000 + $150 + ($70 x 6 x 4) = $3830
Yes, Mr Lim will be able to cover his costs from his earnings
Date Posted:
3 years ago
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