The average rainfall for 6 months was 28.5 mm.If it had rained 1 mm more eache month what would the average have been?By how much would the total have been increased in six months and by how much would average have been increased per month.
If all scores increase by a certain amount, the mean will be increased by the same amount.
For the second question, I'm not sure what you mean by "total." Total what?
For the third question, it is answered in your first question.
I hope this helps. Thanks for asking.