This was posted by someone on the apstat list ... and, seems like an interesting problem to pass along to you.

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A class of 5 students took a test on statistics. The results were Ann - 70,
Belinda - 40, Cal - 40, Daniel - 40 and Erika - 40. The teacher standardised
the scores. Ann earned a z-score of 1.79 (to 2 decimal places).

The next week the same class took another test. Ann studied really hard and
blitzed the test. The results were Ann - 100, Belinda - 40, Cal - 40, Daniel -
40 and Erika - 40. Ann was really proud of her achievement. But then the
teacher standardised the scores. Ann was devastated - her z-score was still
1.79.

Ann decided that studying hard was a waste of time so she decided to watch TV
instead of study. The results on that week's test were predictable: Ann - 45,
Belinda - 40, Cal - 40, Daniel - 40 and Erika - 40. Ann thought that maybe she
should have studied after all. But then the teacher standardised the scores.
Ann was right the first time - studying is a waste of time! Her z-score was
still 1.79.

What gives?
[This remarkable result is from an article in the Australian Senior Mathematics
Journal, Vol 17, No 1, by Ed Staples



---------------------------------------------------------- Dennis Roberts Email: [EMAIL PROTECTED] Web: http://roberts.ed.psu.edu/users/droberts/drober~1.htm

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