Question

Question #4927a

Answer 1

`81:1`

Explanation:

Ratio of radii `r1:r2=9:1`
Ratio of areas `pir_1^2:pir_2^2` `or r_1^2:r_2^2=9^2:1^2=81:1`

Answer 2

`81:1`

Explanation:

In general

`"ratio of areas"::"(ratio of lengths)"^2`

in this case

`"ratio of lengths"::9:1`

`:."ratio of areas"::(9:1)^2::81:1`