Help I don't know what mean is.
Mean is finding the average of a group of numbers. Add the numbers up and divide by the amount of numbers e.g. if the numbers are 5, 10, 15, 20 and 25 add them together =75. Now divide by 5 (because their are 5 numbers)
Your answer is 15. Hope this helps.
The difference between the highest number and smallest number. E.g. say the numbers are 5, 15, 25, 35 and 45 to get the range subtract 5 from 45 (45-5) to find the range. The answer is 40.