Mirroring WordPress Site – Multiple Installs On 1 Database?

I am currently working on a project where the client has wordpress installed on a subdirectory, but wants the new home page design to show on the root domain.

Is it possible to install wordpress onto the root directory and have it pull from the database of the other installation so that it will show some of the recent blog posts on the home page?

Or is there another solution?

Any help is appreciated, thank you!