A P Statistics
Name:
Directions:
Work on these sheets.
A random digit table is attached.
Part 1:
Multiple Choice.
Circle the letter corresponding to the best answer.
1.
In a large population of college students, 20% of the students have experienced feelings of math
anxiety.
If you take a random sample of 10 students from this population, the probability that
exactly 2 students have experienced math anxiety is
(a) 0.3020
(b) 0.2634
(c) 0.2013
(d) 0.5
(e) 1
(f) None of the above
2.
Refer to the previous problem.
The standard deviation of the number of students in the sample
who have experienced math anxiety is
(a) 0.0160
(b) 1.265
(c) 0.2530
(d) 1
(e)
.2070
3.
In a certain large population, 40% of households have a total annual income of
at least
$70,000.
A simple random sample of 4 of these households is selected.
What is the probability that 2 or
more of the households in the survey have an annual income of
at least
$70,000?
(a) 0.3456
Bad wording in this question.
I’ve improved it, above, in blue.
(b) 0.4000
(c) 0.5000
(d) 0.5248
(e) The answer cannot be computed from the information given.
4.
A factory makes silicon chips for use in computers.
It is known that about 90% of the chips
meets specifications.
Every hour a sample of 18 chips is selected at random for testing.
Assume a binomial distribution is valid.
Suppose we collect a large number of these samples of
18 chips and determine the number meeting specifications in each sample.
What is the
approximate mean of the number of chips meeting specifications?
(a) 16.20
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 Spring '11
 MR.Smith
 Probability theory, #, 20%, $70,000, #passes

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