Error in an exam pilot paper answer sheet

I don't see how this formula can possibly lead to the answer given below;
It relates to an accountancy exam paper and I presume it is a printing error, or is it?

= √(.6)²(.0588)² + (.4)²(.046)² + (2)(.6)(.4)(.75)(.0588)(.046)

= √25.57 = 5.06