How can we prepare for exam when 15 day are left

1st step, DON'T PANIC. You have plenty of time to study. When it's a big exam, I like to set aside 2 hours daily for studying. If you're confused by certain topics, watch a video or ask your professor how to properly complete the answer. One college tip I learned: ALWAYS ASK THE PROFESSOR IF YOU GET CONFUSED WHILE STUDYING! They can help clear up problems you have. On the night before the exam, make sure you get a good night's rest. On the day of your exam, make sure to eat a good breakfast.

You have plenty of time, you got this! :)

one fourth of 9% = 2.25%

gavin is correct in saying : the equivalent quarterly interest rate would be

2.25%.