rounding up?

[Asimov Pupil]

how bout -49.5?

 

do you round to -50 or -49

 

or is "rounding up" an improper term.

[donkey]

lol, i'd always say -50 but that's an interesting point

[MathsIsFun]

It is all about fairness. Gotta have the same number of players on each team.

 

0,1,2,3 and 4 are on team "down"

5,6,7,8 and 9 are on team "up"

 

So -49.5 joins its fellows -49.6, -49.7, -49.8 and -49.9

 

[BigMoosie]

Yes, I asked my teacher this once and she replied to -50. They should call it rounding away from zero.

[Dave]

I'm inclined to agree with -50, myself. I never really considered it.

[MathsIsFun]

OK, we can test which is best.

 

Say you are estimating your supermarket bill. Round off everything to the dollar, add em up and see how close you get to the answer.

 

Pretend they are all negative numbers, in fact they are!

 

If you have -49.5 becoming -49 then there will be 6/10 (0,1,2,3,4 and 5) being made closer to zero vs 4/10 (6,7,8,9) being made further from zero. This should bias your estimate.

 

So, it is better to have 5 joining 6,7,8 and 9.

[BigMoosie]

Hey, it is biased whichever way you go.

 

Here in Australia we have always rounded to the nearest 5 cents, soon we are getting rid of that coin and it will be to the nearest 10 cents (blame inflation). That sux because now 5/9 of the time it is rounded up and 4/9 of the time down. Before there was no bias at all .