a)
All of the parents of professional golfers.
b)
The 300 professional golfers surveyed.
c)
The parents of the 300 golfers surveyed.
WORK IT OUT PROBLEMS!
11.
You want to estimate the average starting salary for recent business majors and you
want the margin of error of your results to be no more than $500. Assume that the
standard deviation of starting salaries for all recent business major graduates is $8000
and that you want to have 95% confidence in your results. What should your sample
size be?
n=(Z*sd/MOE)^2=983.45
984 ppl
ANS______984ppl_____
2
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#1213: A toothpaste company sells toothpaste tubes that are labeled 6.0 ounces on the
package. You want to see if they are being true to what their label says. You want to
estimate the average fill amount for the toothpaste tubes based on your own data. You
took a random sample of 200 tubes of toothpaste and your computer output is shown
below. Assume the standard deviation of the population of all toothpaste tubes is 0.5
ounces.
Descriptive Statistics: Weight
(ounces)
Variable
Count
Mean
Weight
200
5.6
12. Find a 95% confidence interval for mean weight of all the toothpaste tubes filled by
this company based on your data.
n=200
sd=0.5
xbar=5.6
so 95% CI is (5.61.96*0.5/sqrt(200), 5.6+1.96*0.5/sqrt(200))=(5.53,5.67) ounces
13. Based on your confidence interval, is the company filling their toothpaste tubes with
the labeled amount (6.0 ounces) on average? Explain (12 sentences only.)
No. Because it is outside of 95% CI.
#1415: You want to estimate the average price of a house in Columbus, OH. You want
the margin of error to be no more than $1000. Prior data shows the standard deviation
of house prices is
$10,000.
14. Suppose your sample of size 100 had an average house price of $170,000. Use this
information to give your best estimate for the average house price for all homes in
Columbus, OH.
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 Spring '07
 rumseyjohnson
 Statistics, Normal Distribution, Standard Deviation

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