eXtremely Boost your machine learning Exercises (Part-1)

It is very powerful algorithm that use an ensemble of weak learners to obtain a strong learner. Its R implementation is available in xgboost package and it is really worth including into anyone's machine learning portfolio. This is the first part of eXtremely Boost your machine learning series. For other parts follow the tag xgboost. Answers to the exercises are available here. If you obtained a different (correct) answer than those listed on the solutions page, please feel free to post your answer as a comment on that page.