All the other bits of the Normal Distribution

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All the other bits of the Normal Distribution
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Missing bits
Firstly To use a normal distribution the data
must be independent. Secondly The normal
distribution is only appropriate for continuous
data. Thirdly Watch out for these Compared
to these
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Working Sdrawkcab
Up until now we have been finding out what
proportion in higher, lower or between points.
However, another use of the normal distribution
is to say I want 10 of people to get an A at A
level and from this work out what mark you should
get to gain an A (little bit of politics)
Example Marks in A level Psychology are found
to follow a normal distribution with mean 120
marks and standard deviation of 40 marks. A
dodgy government minister says that this year
only 10 of people should get A grades. What
should be the mark to get an A?
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• 1. P(Y lt C) 0.7
• 2. P(Y gt C) 0.005
• 3. P(Y lt C) 0.95
• P(Y gt C) 0.15
• P(Y lt C) 0.05
• P(Y gt C) 0.8

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Simultaneous Equations
A machine fills large bags of sand, the weights
of which are distributed normally. It is known
that 5 of the bags are heavier than 111.515kg,
while 30 are lighter than 96.92kg. Find the
mean and standard deviation