and normally distributed. The mean length of a link is 10. 95% of all links have a length

between 9 and 11. The total length of each chain is the sum of the lengths of its links. You

consider chains with 100 links

2. How probable is it that such a chain has a total length between 900 and 1100? Answer is 1, but I don't understand the reasoning behind it

3. How probable is it that such a chain has a total length between 990 and 1010?

4. How probable is it that such a chain has a total length between 999 and 1001?