Rounding

[JNichols]

My daughter in the 8th grade came home with homework on averages for speed.

Distance	Time	V
2	9	0.222222
2	13	0.153846
2	11	0.181818
	mean	0.185962
	stdev	0.034376

The closest answer was 0.18 m/s.  It made me think of the stuff we were talking about the other day about rounding.  I chuckled and thought of you lot. 

Clearly you tell your 13 yr old daughter the answer is 0.18, and you 

1.  do not raise an issue with the teacher as she is doing metric problems

2. raise the issue with the teacher as a concerned engineer that answers need to be accurate.  

If you answered 2 - interesting, but it is the wrong answer as it will not win you any friends and may alienate your daughter's teacher.  

Rounding obeys higher rules than set out in the manuals. 

[andrew_4619]

But the  answer is maybe 0.181818 as 6 units of distance were complete in 33 units of time.....?

[JohnNichols]

Yes that is the way my daughter was taught.   

Interesting actually - just from a pedagogical viewpoint. 

I was happy she was being taught metric in Texas. 

[jimdempseyatthecove]

>>The closest answer was 0.18 m/s. 

The chart does not indicate the units of measure. So the answer would be .18(.1818...) unit velocities.

Jim Dempsey

[JohnNichols]

My apologies, it is an 8th grade math problem - they are just learning about length and time to get velocity.  

It is interesting to read the problems. sometimes you can know to much.  

ie, what is the bottom of the theoretical physics well?