Taking a collection of qualifications as a List, obtain the average grade of the students who have passed the exam.
You must overload the invoke to function with markLimit to obtain the average of all the grades that are greater than this limit.
val listOfGrades = listOf(5.5, 4.6, 3.0, 2.5, 10.0, 9.9, 8.75)
println(listOfGrades(5.0))