Stat 350 Practice Problems for Exam 1
(Spring 2011)
First Set
1.
Suppose that values are repeatedly chosen from a standard normal distribution.
a) In the long run, what proportion of values will be less than 1.06?
b) What is the longrun proportion of values that will be between 1.50 and 2.50?
c) How large must a value be to be among the largest 20% of all values selected?
2.
The pollutants a factory dumps into a river every week has a normally distribution.
The factory
dumps an average of 2.43 tons of pollutants into a river every week. If the standard deviation is
0.88 tons, what is the probability that in a week more than 3 tons are dumped?
3. The noise level in a restaurant has a normal distribution with
= 30 (dB) with
= 4 (dB).
Find
the value c so that 99% of the time the noise level is below c.
4. The amount of coffee dispensed by a certain machine has a normal distribution with
= 20 oz
and
= 2 oz. What container size c will ensure that overflow occurs only 2% of the time?
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 Spring '08
 Staff
 Normal Distribution, Probability theory, telephone lines, location time

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