Explanation:
Number 5
Range is the highest value subtracted by the lowest value
So the highest value in the chart is 370 and the lowest is 280.
370 - 280 = 130 not 90
Number 6
Calculate the mean (average) of the numbers.
Subtract the mean from each number and square the result.
Calculate the mean of the squared differences.
Take the square root of the mean of the squared differences.