Is my iMac running Mavericks? I am looking for Mavericks on my iMac. I have looked in Finder but I do not see it there. How can I find out if Mavericks was installed on my iMac?
Go the to the Apple menu (top left) => About this mac. 

The existing versions are following : 


OS X 10.10 Yosemite
OS X 10.9 Mavericks
OS X 10.8 Mountain Lion
OS X 10.7 Lion