For ice skating on a frozen pond to be safe, the ice should be at least 7 inches thick. Estimate the date on which it first became safe to ice skate.
|
Date
|
Thickness
|
|
December 4
|
3 in.
|
|
December 16
|
4 in.
|
|
January 4
|
5 in.
|
|
January 16
|
11 in.
|
|
February 2
|
17 in.
|