Before we dig deep into your problem, let me ask you several questions?
Firstly, what is the average score?
if you are within the upper 50%, the problem is not so serious.
Secondly, which part of the exam you didn't do well?
I mean multiple choice or simple answer?
The last but not the least,
you may talk to your instructor directly,
she/he will offer you the most authoritative answer to your inquiry.
Generally speaking, managerial courses are not that hard.
That's why so many engineering students shift their major at graduate level.
Take it easy,
you can make it finally.
I hope it helps.