If a : 2b = 2 : 5 and b : c = 3 : 2, then which of the following is a : b : c?
2019
If a : 2b = 2 : 5 and b : c = 3 : 2, then which of the following is a : b : c?
- A.
6 : 10 : 15
- B.
6 : 15 : 10
- C.
12 : 15 : 10
- D.
15 : 12 : 10
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Correct answer: C
Solution: Combine the given ratios step by step.
From a : 2b = 2 : 5, write a/(2b) = 2/5. This gives a = (4/5) b, so a : b = 4 : 5.
From b : c = 3 : 2 we have b : c = 3 : 2.
Make the b terms equal: LCM of 5 and 3 is 15. Scale a : b = 4 : 5 by 3 to get 12 : 15. Scale b : c = 3 : 2 by 5 to get 15 : 10. Combine to get a : b : c = 12 : 15 : 10.
Answer: 12 : 15 : 10