DB : Installing oracle database fails with inventory owner permission denied

When installing new database as "oratest" new user on the existing server with other databases running in it the installation failed with below error

Error:

[oratest@myserver database]$ ./runInstaller
You do not have sufficient permissions to access the inventory '/d01/oracle/app/oraInventory'. Installation cannot continue. It is required that the primary group of the install user is same as the inventory owner group. Make sure that the install user is part of the inventory owner group and restart the installer.: Permission denied
[oratest@myserver database]$

Solution:
Change the oratest user group to same as the group of oraInventory

As a root user change the "oratest" group to "dba" as below

useradd -G dba oratest