Confidence Interval for ISO Certification
Not what you're looking for?
In a random sample of 100 manufacturing firms, 67 indicated that their company attained ISO certification within the last two years. Find a 95% confidence interval for the population proportion of companies that have been certified within the last two years. In solving the above question you must write the formula of the confidence interval and show necessary calculations.
The total amount of hydrogen chloride (HCL) in columns above an altitude of 12 km was measured at selected sites over a certain volcano both before and after an eruption. The summary of the samples are as follows:
Preeruption (X) Posteruption (Y)
n_1 = 40 n_2 = 20
X = 1.28 Y = 1.40
s_1 = 0.14 s_2 = 0.04
a) First test at 5% level of significance whether the population variance of X and Y are equal or not.
b) Next test at 5% level of significance whether the population mean of X and Y are equal or not. Your choice of test must based on the result of part (a).
For both tests clearly state the hypotheses, formula and value of test statistics, rejection region and the final conclusion.
Purchase this Solution
Solution Summary
The solution provides step by step method for the calculation of c . Formula for the calculation and Interpretations of the results are also included.
Solution Preview
Please see the attachment.
Answer
Question 1
Confidence interval for proportion is given by
Details
Confidence Interval Estimate for the Mean
Data
Sample Size 100
Number of Successes 67
Confidence Level 95%
Intermediate Calculations
Sample Proportion 0.67
Z Value 1.95996398
Standard Error of the Proportion 0.047021272
Interval Half Width 0.092159999
Confidence Interval
Interval Lower Limit 0.577840001
Interval Upper Limit 0.762159999
a).
H0: There is no significant difference in the population variance of X and ...
Purchase this Solution
Free BrainMass Quizzes
Know Your Statistical Concepts
Each question is a choice-summary multiple choice question that presents you with a statistical concept and then 4 numbered statements. You must decide which (if any) of the numbered statements is/are true as they relate to the statistical concept.
Measures of Central Tendency
This quiz evaluates the students understanding of the measures of central tendency seen in statistics. This quiz is specifically designed to incorporate the measures of central tendency as they relate to psychological research.
Measures of Central Tendency
Tests knowledge of the three main measures of central tendency, including some simple calculation questions.
Terms and Definitions for Statistics
This quiz covers basic terms and definitions of statistics.