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The manufacturer of hardness testing equipment uses​ steel-ballindenters to penetrate metal that is being tested.​ However, themanufacturer thinks it would be better to use a diamond indenter sothat all types of metal can be tested. Because of differencesbetween the two types of​ indenters, it is suspected that the twomethods will produce different hardness readings. The metalspecimens to be tested are large enough so that two indentions canbe made.​ Therefore, the manufacturer uses both indenters on eachspecimen and compares the hardness readings. Construct a​ 95%confidence interval to judge whether the two indenters result indifferent measurements.

​Note: A normal probability plot and boxplot of the dataindicate that the differences are approximately normallydistributed with no outliers.

Specimen   Steel ball   Diamond
1   51   53
2   57   55
3   61   63
4   71   74
5   68   69
6   54   55
7   65   68
8   51   51
9   53   56

Construct a​ 95% confidence interval to judge whether the twoindenters result in different​ measurements, where the differencesare computed as​ 'diamond minus steel​ ball'.

The lower bound is __?__ .

The upper bound is __?__. ​

(Round to the nearest tenth as​ needed.)