The National Safety Council reports the following age breakdown for licensed drivers in the United States.
Age (Years) Licensed Drivers (Millions)
under ...............20 10.72
20–under 25 ............16.84
25–under 35 ............40.78
35–under 45 ............45.59
45–under 55 ............36.70
55–under 65 ............23.32
65 or over .............28.76
Identify the following for the 35–under 45 class:
(a) Frequency,
(b) Upper and lower limits,
(c) Width, and
(d) Midpoint.