My brother got selected for the JNCASR SRFP program a few years back, for Chemical Sciences. He had a decent GPA and average research background. He wrote his application in simple language expressing why he want to pursue the program. Based on my brother’s experience, I will say the institute don’t select student based just on their GPA. In your application, state clearly why you want to pursue science. If you want to apply for the summer program, make sure you state your passion for science.