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Secondary 1 | Maths
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Did I do this correctly? Sorry I was unsure on what method to use.
Date Posted: 4 years ago
Views: 301
Hi NL, methods and answers for both qns are right. For (ii), suggest using mins instead of secs.
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Hi there!
For the first part of first question, your answer is correct. Finding HCF is the correct method.
However, you might wish to consider writing out your numbers as a product of prime factors (which is both neater and easier to visualize).
1155: 3 × 5 × 7 × 11
462: 2 × 3 × 7 × 11
693: 3^2 × 7 × 11
HCF = 3 × 7 × 11 = 231
For the second question, now you wanna find the LCM instead (for when the security guards meet again).
Similarly, write the values out in product of prime factors as such:
A (24): 2^3 × 3
B (36): 2^2 × 3^2
C (60): 2^2 × 3 × 5
LCM (take all factors and all largest ones) =
2^3 × 3^2 × 5 = 360 or 5hours
Cheers!
For the first part of first question, your answer is correct. Finding HCF is the correct method.
However, you might wish to consider writing out your numbers as a product of prime factors (which is both neater and easier to visualize).
1155: 3 × 5 × 7 × 11
462: 2 × 3 × 7 × 11
693: 3^2 × 7 × 11
HCF = 3 × 7 × 11 = 231
For the second question, now you wanna find the LCM instead (for when the security guards meet again).
Similarly, write the values out in product of prime factors as such:
A (24): 2^3 × 3
B (36): 2^2 × 3^2
C (60): 2^2 × 3 × 5
LCM (take all factors and all largest ones) =
2^3 × 3^2 × 5 = 360 or 5hours
Cheers!
Sorry, its 6 hours at the end (mistyped).
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