A-3 Test Results problem

Imagine that you are a teacher and you have collected the results from a test of your 10 students in one place. The test results are numbers from 1 to 100.  The basis is 50. Calculate what percentage of the class has not passed the basis.

The results are the followed: 78, 82, 45, 69, 23, 91, 55, 39, 66, 60.