A random sample of a town population is summarized by the following frequency distribution:
Age (years) Number of Residents
0 ≤ x < 20 620
20 ≤ x < 40 800
40 ≤ x < 60 550
60 ≤ x < 80 400
80 ≤ x < 100 120
Round your answers to two decimal places as needed.
Mean: _____
Variance: _____
Standard Deviation: ______
Range of Variation (one-standard deviation interval):
(bow, high) = ( _______, _______)