Depends on how fast you're going. Not long though.
You didn't tell us how long it took to walk those 3.33 meters, so it is impossible to know how long 100 meters would take.
0.688 acres
36 hours
100' x 500' = 1.14 acres
.3 builders acres
It depends on the pace of the person walking
Answer: 29,000 ft² = 0.665748 acres.
2.56 acres (US)
assuming walking speed = 100 meter/minute 1200 meters take 1200/100 = 12 minutes
You would walk one metre in 3.8/6 = 19/30 seconds. Therefore, 100 metres would take 19/30 x 100 = 63.3 recurring (that is, 63.333...) seconds.
That depends entirely at what speed she's walking !