Answer:
The correct answer is d) All of these are correct.
Explanation:
ETL stands for Extract, Transform and Load. An ETL system extracts data from the sources, enforces data quality and consistency standards, conforms data so that separated and maybe unrelated sources can be used together, and as a final step delivers data in presentation-ready formats so that developers can build applications and end users can take decisions.
<em><u>Answer</u></em>
5 hours
<em><u>Explanation</u></em>
The two working together can finish a job in

Also, working alone, one machine would take one hour longer than the other to complete the same job.
Let the slower machine working alone take x hours. Then the faster machine takes x-1 hours to complete the same task working alone.
Their combined rate in terms of x is

This should be equal to 20/9 hours.

Multiply through by;





Factor to get:


It is not feasible for the slower machine to complete the work alone in 4/9 hours if the two will finish in 20/9 hours.
Therefore the slower finish in 5 hours.