Answer:
Ratio defined as the comparison of two size or number.
i.,e

As per the statement:
There are 346 students enrolled in a math course and 488 students enrolled in a history course.
⇒Students enrolled in a math course = 346
and
Students enrolled in a history course = 488
By definition of ratio:

or

Therefore, a ratio comparing students enrolled in a math course to students enrolled in a history course is 0.709