
Concept explainers
QUESTION 4
Titus Company, a recycling computer company ordered computer components from two different
suppliers, namely Supplier A and Supplier B. Since Covid-19 outbreak in Malaysia, the company
has financial constraint and need to identify which supplier has more reliable component. During
assembly process, the number of defective components is recorded. The number of defective
components for each supplier from 12 random days in a month is given in Table 3. Assume that
the data are
Table 3
Day 1 2 3 4 5 6 7 8 9 10 11 12
Supplier A 34 36 40 39 30 38 37 39 35 41 40 38
Supplier B 40 40 38 39 37 35 42 41 40 41 33 39
(i) Construct a 90% confidence interval for the difference in the true average number of defective
components between both suppliers.
(ii) Interpret the parameter estimate obtained in (i)?
(iii) What is the effect on the confidence interval in (i) if the value of significance level increases?

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