Wikipedia:Reference desk/Archives/Mathematics/2017 June 18

= June 18 =

What's the distance?
A boat take 23 min 35 secs to complete a course at average speed of 23.21 knots. How far has it travelled in miles, and how far in metres? Moriori (talk) 02:53, 18 June 2017 (UTC)
 * --Jasper Deng (talk) 03:02, 18 June 2017 (UTC)
 * (Yes, I know you've probably asked questions here before, but I firmly believe we shouldn't work out solutions without the asker first trying; knots = nautical mile/s).--Jasper Deng (talk) 03:03, 18 June 2017 (UTC)
 * Your apology is accepted. The figures I gave came from an actual America's Cup race this morning. I casually asked a couple of friends what the distance travelled would be, and got two different answers. Eureka, I know, I said, I'll ask at the wiki maths reference section which has all sorts of boffins involved. Unfriendly testy ones too I see. Moriori (talk) 03:19, 18 June 2017 (UTC)
 * Well, if you will use the same sort of wording that a homework problem would, it shouldn't be surprising if people think that's what you're doing!
 * A nautical mile is 1852 meters, but a knot is one nautical mile per hour (3600 seconds), not per second as Jasper said. So the distance in meters is 1852 × 23.21 × (23×60 + 35) / 3600 = 16,895 m, which should be rounded to 16,900 m since the inputs only have 4 significant digits.  Now a mile is 1609.344 m; so divide by that number and you get 10.50 miles. --76.71.5.114 (talk) 06:26, 18 June 2017 (UTC)
 * My bad, I'm so used to using seconds for time. --Jasper Deng (talk) 07:44, 18 June 2017 (UTC)


 * Reasonableness check - a nautical mile is a bit longer than a statute mile. So we have a boat travelling at a little more than 20 mph for a little less than half an hour. So ballpark answer is 10 miles. Gandalf61 (talk) 09:45, 19 June 2017 (UTC)