The line graph illustrates three companies’ time consumed on manufacturing a refrigerator over a period of ten years.
Overall, company B and company C exhibeted a slightly decreasing tendency, while company C remained stable.
To be specific, though commencing at 35 hours in 1990 and experienced a continuous decline, reaching lower than 30 hours in 2000, company C always had the highest usage on making a refrigerator. A similar trajectory can be seen in company A, which needed about 30 hours in 1990, and dropped to lower than 25 hours at the end of the period. Noteworthy changes can be oberved in company B, whose time consumed on making a refrigerator represented a stable progress, maitaining more than 25 hours through this period.
It is remarkable that the time usage of company A was higher than company B at the beginning of the period. However, after years of progress company A reached the same level as company B and finally overtook B becoming the second efficency company.
