How to check the age of your iPhone 4s?

Hi, I recently brought a brandnew iPhone 4s from ebay and it was sealed ect and i was just wondering how you can tell the actual age of the phone using the serial number or IMEI/MEID number?

There are two steps to confirming how old the phone is

1, the year the iPhone was made could be ascertained by either the year the phone was bought brand new which usually coincides with the year Apple releases it, so the iPhone 4s is 2011.

2, The 2nd and 3rd numbers in the serial number of the iPhone 4s. Go to Setting>About to find the serial number. The two numbers together denote the week number eg. 38 is week 38 of 2001.