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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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