Here is the CSU/UC GPA calculator using only 10-11 th grades: http://rogerhub.com/gpa-calculator-uc/
For UC Merced, you will need at the minimum a GPA of 3.0 to qualify to apply, however; that will not necessarily mean you have a good chance for an acceptance.
To really chance you, you need to post your Test scores since all the Cal States use the Eligiblity index calculation to rank applicants.
(CSU GPA X800) + (SAT MATH + CR) OR (CSU GPAX200) + (ACT COMPOSITE)
Intended major will also make a difference on your chances. Repost with the needed information.