How do you calculate a Standard Deviation?
>>> "Lambourne Adrian (QEX) HERTS-HA"
<[log in to unmask]> 04/09/02 05:33pm >>>
Can I suggest that this sort of query is not an appropriate use of
AllStat.
I would have hoped that a course tutor at Paul's college/school was
the
person to contact for A level statistics queries.
We may soon have queries such as 'How do you calculate a standard
deviation?'
Adrian Lambourne
Head of Health Information
Hertfordshire Health Informatics Service (HHIS)
-----Original Message-----
From: Caroline.Lynch [mailto:[log in to unmask]]
Sent: 09 April 2002 17:13
To: [log in to unmask]
Subject: Re: Help wanted with my a Level Stats project pleeeses!
Might I suggest that he already tried the book? Haven't you ever read a
book
you didn't understand? I was always led to believe that if you don't
understand something, you should ask someone who might be able to help
you!
Caroline Lynch
University of Limerick
-----Original Message-----
From: Paul R Swank [mailto:[log in to unmask]]
Sent: 09 April 2002 16:43
To: [log in to unmask]
Subject: Re: Help wanted with my a Level Stats project pleeeses!
All I can say is that if you can't solve that problem you need to go
back to
the book.
Paul R. Swank, Ph.D.
Professor, Developmental Pediatrics
Medical School
UT Health Science Center at Houston
-----Original Message-----
From: A UK-based worldwide e-mail broadcast system mailing list
[mailto:[log in to unmask]]On Behalf Of bryanjeanes
Sent: Tuesday, April 09, 2002 8:53 AM
To: [log in to unmask]
Subject: Help wanted with my a Level Stats project pleeeses!
Hello everybody, I am trying without much success to complete my A
level
course work and I would be extremely appreciative and grateful if
anybody on the Allstat list would be kind enough to give up a few
minutes of their precious time to help me. I appreciate that your time
is very valuable so I will post the two types of problem with which I
am
having difficulty with the hope that somebody will have the time to
help
me. Yours hopefully, Bryan Jeanes, 17, Crosskeys College of F.E.
Newport, Gwent.
1. A local community was concerned about the speed of commercial
traffic
in a residential area where the speed limit is set at 48km/h (30mph).
A
survey showed that the average speed of commercial vehicles was 54km/h
and the standard deviation was 9.5km/h. The distribution of speeds
approximated that of the normal distribution.
(a) What percentage of commercial vehicles exceed the speed limit?
(b) What percentage of vehicles exceed 72km/h (45mph)?
(c) Between what speeds does the in interquartile range (the middle
50%)
fall?
2. A survey using a sample of 56 customers of a courier company
revealed
that 72% were highly satisfied with the timing of their deliveries.
Using the 95% confidence interval, calculate the percentage range of
the
population of customers who were highly satisfied.
(b) What sample size would be required to achieve a level of accuracy
within the population of plus or minus 3%?
I hope that somebody will be able to help, Cheers, Bryan.
PS, These are not the exact questions as I don't want the work done
for
me , I just want worked answers to similar questions so that I can
follow the procedures and formulas to answer the actula problems on my
paper. To these ends I have posted two problems that are broadly
similar
to the ones that I am having difficulty with. Thanks.
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