1.

Eight numbers are in geometric progression. Their sum is 21 and the sum of their reciprocals is 7. Their product is :A. 243B. 32C. 81D. 162

Answer» Correct Answer - C
`a+ar..........+ar^(7)=21`
`"and" " "(1)/(a)+(1)/(ar)+.......+(1)/(ar^(7))=7impliesa^(2)r^(7)=3`
`therefore" "a^(8)r^(28)=81`


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