125: Average Shmaverage

Assume a classroom where every grade has equal weight. Here are two sets of grades:
Student A (ave=80.0): 100, 100, 100,  0,  100
Student B (ave=80.2):  81,  80,   80,  80,  80

Questions:

1. Who has better mastery? 
2. Who will be better prepared for the next course?
3. Which would you rather be?

Another set of grades, in sequence:
Student A: 25, 25, 50, 100, 100
Student B: 100, 100, 50, 25, 25

Same questions:

1. Who has better mastery? 
2. Who will be better prepared for the next course?
3. Which would you rather be?

Examples from Step 1: Try Something.