City Guilds Model Questions Vol1 2020 Information Technology Question 49
Practice objective / multiple choice question 49 from the 2020 City Guilds Model Questions Vol1 Information Technology examination.
Table **Employees** contains 12 000 rows and Table **Departments** contains 150 rows. Each employee belongs to exactly one department (foreign key). A query joins the two tables on *department_id* and then applies two selection conditions: (i) *salary* > 80 000, which selects 30 % of the employees, and (ii) *location* = 'Lagos' in the Departments table, which selects 40 % of the departments. Assuming the two conditions are independent and that employees are uniformly distributed among departments, estimate the number of rows returned by the query.
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About This Question
This is City Guilds Model Questions Vol1 2020 Information Technology Question 49. It is one of the objective questions from the 2020 City Guilds Model Questions Vol1 Information Technology examination.
Difficulty level: Medium .
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