A Company Manufacturing Details for the Large Machinery Updates Its

Multiple Choice

A company manufacturing details for the large machinery updates its milling machines. When at the first factory all the milling machines were replaced with the new ones, it was decided to conduct a study in order to define whether the average production time of one detail had decreased. For this purpose, at each of the company's factories (note that Factory A has only new milling machines and three other factories have both old and new milling machines) , a sample determining the average production time of one detail had been generated. The result of this study is shown on the following underscoring pattern. Interpret this underscoring pattern.

A) Average time of making one detail for the factories A and D differ from the average time for the factories B and C.
B) Average time of making one detail for all the factories is the same.
C) Average time of making one detail for the factory A differs from the average time for the factories B, C and D.
D) Average time of making one detail for the factory A differs from the average time for the factories B and C, and other three factories have equal average time.