MTH 380 Lecture Notes - Lecture 9: Point Estimation, Variance, Standard Deviation

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22 Nov 2020
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1
ASSIGNMENT 9, Estimating the difference between two population means and two
population proportion
Part 1
Chapter 8, Large - Sample estimation
Ch.8.4. Estimating the difference between two population means
1.Ch.8.4, 1 & 3, p.311
Independent random samples were selected from two quantitative populations. The
sample sizes, sample means and variances are given in the table below:
Population
1 2
_______________________________________________
Sample size 35 49
Sample mean 9.7 7.4
Sample variance 10.78 16.44
Find 90% and 99% confidence intervals for estimating the difference in population means.
Can you conclude with 90% confidence that there is a difference in the means for the two
populations? With 99% confidence?
2. Ch.8.4, Review, 3, p.330
Independent random samples of
150
n
=
and
260n=
observations were selected
from populations 1 and 2, respectively. The sample sizes and computed sample statistics
are given in the table:
Population
1 2
_______________________________________________
Sample size 50 60
Sample mean 100.4 96.2
Sample variance 0.8 1.3
Find 90% confidence intervals for the difference in population means.
Suppose you wish to estimate
12
µµ
correct to within 0.2, with probability equal to 0.95.
If you plan to use equal sample sizes, how large should
1
n
and
2
n
be?
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2
3. Ch.8.4, 11, p.311
4. Ch.8.4, 12, p.311
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