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Q 3.3 -

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Question

Q 3.3

Sum

Solution

Let G1, G2, G3, G4, G5 be five geometric means between a = `3 5/9=32/9` and b = `40 1/2=81/2`

Then, `32/9`, G1, G2, G3, G4, G5, `81/2` is a G.P.
Thus, we have
First term = a = `32/9`
7th term of the G.P. = ar6 = `81/2`

⇒ `32/9` x r6 = `81/2`

⇒ r6 = `81/2xx9/32`

⇒ r6 = `729/64`

⇒ r6 = `(3/2)^6`

⇒ r = `3/2`

∴ G1 = ar = `32/9xx3/2 = 16/3`

 G2 = ar2 = `32/9xx9/4 = 8`

G3 = ar3 = `32/9xx27/8 = 12`

G4 = ar4 = `32/9xx81/16 = 18`

G5 = ar5 = `32/9xx243/32 = 27`

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Simple Applications - Geometric Progression
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