There are n arithmetic means between 9 and 27. If the ratio of the last mean to the first mean is 2:1, find the value of n.
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Given: there are n arithmetic means between 9 and 27
To find: if the ratio of the last mean to the first mean is 2 : 1, then find the value of n
Solution:
- Let the common difference be d
- Then the first mean is 9 + d
- and the last mean is 27 - d
By the given condition,
- 27 - d : 9 + d = 2 : 1
- or, (27 - d) / (9 + d) = 2 / 1
- or, 27 - d = 2 (9 + d)
- or, 27 - d = 18 + 2d
- or, 2d + d = 27 - 18
- or, 3d = 9
- or, d = 9 / 3
- or, d = 3
Let progression of the arithmetic means is
12, 15, 18, 21, 24.
Thus n = 5
Answer: the value of n is 5.
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Answer:
5 is a correct answer
Step-by-step explanation:
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