A Mean Calculation

What is the mean of this set of numbers?
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
Being curious Being resourceful Being resilient Being collaborative

Problem



Can you work out the mean of this set of numbers without using a calculator?

97   97   98   99   99   99   100   100   101   101   103   104   104   105