The best firm for the Appliance manufacturer for the repair work is Firm 2 .
In the question ,
it is given that ,
An appliance manufacturer wants to contract with a repair shop to handle authorized repairs in Indianapolis .
The acceptable range of the repair time is 50 minutes to 90 minutes.
the mean repair time for firm 1 = 74 minutes and standard deviation of 4 minutes .
the mean repair time for firm 2 = 72 minutes and standard deviation of 5.1 minutes .
the range is calculated using the formula
Range = Mean ± Standard Deviation
So , for firm 1 ,
the Range = 74 ± 4
= 74 4 and 74 - 4
= 78 and 70
the range for firm 2 is
= 72 ± 5.1
= 72 5.1 and 72 - 5.1
= 7.1 and 66.9
The second company has a lower range and it should be preferred .
Therefore , The best firm for the Appliance manufacturer for the repair work is Firm 2 .
Learn more about Standard Deviation here
#SPJ1