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Home » There is 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.
There is 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.
RS aggarwal class 11 Maths Arithmetic progressions
There is 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.

To find: The value of n

Given: (i) The numbers are 9 and 27
(ii) The ratio of the last mean to the first mean is 2 : 1

Formula used: (i) , where, d is the common difference
n is the number of arithmetic means
(ii) An = a + nd
We have 9 and 27,

⇒ 27n + 9 = 18n + 54
⇒ 9n = 45
⇒ n = 5
Ans) The value of n is 5

i

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