Defective electronics:A team of designers was given the task of reducing the defect rate in the manufacture of a certain printed circuit board. The team decided to reconfigure the cooling system. A total of

981

boards were produced the week before the reconfiguration was implemented, and

253

of these were defective. A total of

853

boards were produced the week after reconfiguration, and

180

of these were defective.

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Part 1 of 2

(a)Construct a

99.8%

confidence interval for the decrease in the defective rate after the reconfiguration. Let

p1

denote the proportion of defective boards before the reconfiguration was implemented and

p2

denote the proportion of defective boards after the reconfiguration was implemented. Round the answers to three decimal places.

A

99.8%

confidence interval for the decrease in the defective rate after the reconfiguration is

<<p1p2

.