They just want you to have good foundation for 1st and 2nd year maths in engineering...
I wouldn't worry man, first semester of 2012, I had 82-83% average but I retook chem 2nd semester, and worked really hard for biology and english, and data management and pulled myself up to a 90%... I was worried I was not going to get in to mac eng.... But look what happened
My motto, do the best and forget the rest