Longest Lines of Sight on Earth • Hacker News Board

Re: Longest Lines of Sight on Earth

#161

Post by PhantomGremlin » Fri, Jul 28, 2017, 8:41 AM UTC

Dove wrote: post #154

seanmcdirmid wrote: post #52

Earlier quoted context omitted.

It seems like one of those stupid brain teasers tech companies used to ask that are not very correlated with success but act as arbitrary filters.

I don't see anything tricky about that problem. It requires some junior high geometry and high school trig, and yes, I suppose you need to know the radius of the earth offhand. Still. That strikes me a lot more as a math fizzbuzz than as a brain teaser. A college applicant can be reasonably expected to know this stuff.

I suppose you need to know the radius of the earth offhand.

Or you can easily derive the radius if you remember that a meter was initially defined as 1/10,000,000 of the distance from the equator to the North Pole. So you can easily calculate the Earth's circumference, and from there the radius: 10,000,000 * 4 / 1000 / 3.1416 / 2 = 6366 km.

Wikipedia gives 6371 km as the mean radius.

Re: Longest Lines of Sight on Earth

#162

Post by SamReidHughes » Sun, Jul 30, 2017, 3:50 AM UTC

seanmcdirmid wrote: post #157

SamReidHughes wrote: post #151

Earlier quoted context omitted.

That's a very straightforward math problem.

There is a lot more than the Pythagorean theorem in that question. It would require remember a lot of middle school theorems from a long time ago; frankly calculus would be better.

No. You just need to know circumference = pi times diameter.

Re: Longest Lines of Sight on Earth

#163

Post by [deleted] » Sun, Jul 30, 2017, 5:18 AM UTC

seanmcdirmid wrote: post #133

chrisseaton wrote: post #125

Earlier quoted context omitted.

So why doesn't everyone pass the interview? Either they can't be gamed, or they select for people who can at least be bothered to do the work to game them.

Depends on your resources for prep. Poor kids have less resources for that than rich kids, so they ultimately select for richer candidates.

[deleted]

Re: Longest Lines of Sight on Earth

#164

Post by SamReidHughes » Sun, Jul 30, 2017, 8:37 PM UTC

SamReidHughes wrote: post #162

seanmcdirmid wrote: post #157

Earlier quoted context omitted.

There is a lot more than the Pythagorean theorem in that question. It would require remember a lot of middle school theorems from a long time ago; frankly calculus would be better.

No. You just need to know circumference = pi times diameter.

Or no, I misunderstood the problem. Either way it's a simple problem that entering math majors should be able to solve.