In this study 100 groups of five participants were used to discover problems with an interface. The study did indeed find that the mean percentage of problems discovered across all 100 groups was about 85%. However, this figure has 95% confidence level and a margin of error of Â±18.5%.
Keelboats were generally built in Pittsburgh, Pennsylvania and it was here that Meriwether Lewis commissioned the boat used by the Corps of Discovery. The keelboat used by the Corps was sketched by Clark in his journal. It was 55 feet long and 8 feet wide, with a 3- to 4-foot draft. For propulsion it had a 32-foot sailing mast, 22 oars, a rudder, and a tiller for steering. Protection against hostile encounters were a swivel cannon on the bow and two smaller guns called blunderbusses.
The Governor Albert D. Rossellini BridgeâEvergreen Point bridge (often called just the SR 520 bridge) in Seattle is the longest floating bridge on the planet. It is 7,497 feet (2,285 meters), or 1.4 miles (metric), long and spans Lake Washington, letting vehicles pass to and from Seattle and Bellevue, Washington. After three years of construction, the four-lane toll bridge opened in 1963. It wasn't the first floating bridge on Lake Washington; that was actually the Lake Washington Floating Bridge, which was built in 1940 and wound up as part of Interstate 90. But the SR 520 bridge is significantly bigger than its forbearer. It's four lanes and 60 feet wide and is supported by 33 pontoons. Those individual pontoons are enormous, at around two and a half stories tall, and 360 feet (110 meters) long -- that's longer than four gas tanker semi-trucks placed end to end.