a statistic question -- 會考加油站

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Subject: a statistic question

Author:
xpoon
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Date Posted: 00:22:44 04/04/03 Fri

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Ten thousand candidates sit for a public examination. The marks obtained are normally distributed with mean 50 and standard deviation 10.
[#The passing mark is 40 and the minimum mark for getting grade A is 70.#]
[assume that 68% of the distribution lie within 1*, 95% within 2* and 100% within 3* from the mean]

Question:
The marks are adjusted so that the new mean is 60 and the new standard deviation is 15. Find a and b if the formula for adjustment is y=ax+b where x represents the old mark and y represents the adjusted mark.

The answer in my book are a= 1.5, b= -15

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Replies:

Subject Author Date

Re: a statistic question xpoon 00:24:15 04/04/03 Fri

Re:Sta. Q: What level (CE?AL?) & Where (Maths & Sta? Applied/Pure Maths?) did the Q came from? �O�D 18:32:04 04/07/03 Mon

i think is not a CE ques " CEer" 01:11:29 04/12/03 Sat

Re: i think is not a CE ques -- xpoon, 10:11:00 04/20/03 Sun

Re: a statistic question ipl 10:34:15 04/27/03 Sun

Thanks -- xpoon, 06:43:54 04/30/03 Wed

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