Peter measured the width of one cardboard strip as 2 3/4 ft. A second cardboard strip measured 3 2/3 ft in width. Estimate the combined width of the cardboard strip?

To the nearest foot, the measurements will be 3 ft and 4 ft, for an estimated total of 7 ft. We can round one measurement up to the nearest foot and one down to the nearest half-foot to make the estimation errors nearly cancel. The total then will be 6 1/2 ft.
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The actual total is 6 5/12 ft, or 6 ft 5 in.