Hi Akshayk,
As your MacBook is only 5 days old you are, of course, still under warranty, as well as Apples 14 day no questions asked returns policy. If you believe there is something wrong then go for it!
There are steps you can take in order to prolong your battery life. I recently purchased the same MacBook, had a fiddled with some settings below and now I can go 2-3 days casually browsing and watching Netflix etc. Switch on Battery Percentage so you can track just how much battery is used.
1) Stop Apps opening automatically when you power up your MacBook by heading to - System Preferences > Users and Groups > Your Name > Login Items and removing the ones you don't need open. This goes for Apps that you open also, each active App along your dock uses power so try quitting each App if you find you aren't using them.
2) Brightness - Do you use your Mac on full brightness? This is probably the biggest battery killer of all, as well as a fast way to damage your LED's. I usually have my Retina Display set at around 50% Brightness, and my Keyboard Backlight at 0%. I don't need it, and it kills battery.
3) Mac notebooks have a number of integrated technologies which can have a significant effect on battery power.
- Disable AirPort or Bluetooth from their menu bar icons or in System Preferences (Network and Bluetooth respectively). This will help save power.
- External USB, FireWire, ThunderBolt, SD card, and Expresscard devices added to your notebook may also draw power and should be disconnected for optimal battery performance.
- Eject any CDs or DVDs from the integrated SuperDrive (if available on your notebook) to avoid the drive spinning periodically." - Apple.
4) Do you use Google Chrome? Take a look at This Article by The Verge. It highlights jus how bad Chrome is for your battery life. Do you NEED it? If not, use an alternative such as Safari.
5) To maximize the lifespan of your Lithium Ion battery in your MacBook, use full cycle charges. This means allowing your MacBook to drop below 5% (not off) and then charging it all the way through to 100%. Avoid leaving your MacBook on charge when it reaches 100%.
6) Head to System Preferences > Energy Saver and have a play around with these settings. The sooner you set your mac to sleep etc when idle the more battery you will save.
7) Activity Monitor - If you find your MacBook battery is draining quickly, head to Applications > Utilities > Activity Monitor and set to display activities by Highest CPU Usage, here you will see exactly which programs are running and how much of your system they are hogging. I recently had to disable Safari Top Hits as it was consuming 30%CPU usage on startup and causing my fans to go crazy... I couldn't believe it.
Finally head to Apple Menu > About this Mac > System Report > Hardware > Power and take a look at your Battery Condition. Does it say Normal?
Good luck 🙂