On which day was Yasir born? (His date of birth is February 29) I. He was born between year 2005 and 2011. II. He will complete 4 years on February 29 2012.

Data sufficiency questions are designed to check your ability to analyse & categorise information based on underlying concepts rather than calculations. So you should try to observe -  analyse and to find linkages between various statements rather soing lengthy calculations.