The results of 8 repeated measurements of the same quantity are given below.
measurement value
1 629
2 642
3 650
4 658
5 653
6 645
7 642
8 630
What is the 95% confidence interval for these data? In other words, find mean ± x, where x is the 95% confidence interval and is your answer to this question. Even though it's an uncertainty, express your answer to 2 decimal places.