$($RELATIONAL ALGEBRA$)$ Specify the following queries on the COMPANY

relational database schema shown in Figure $3\mathrm{.}7$ using the relational operators

discussed in Chapter $6.$ Also show the result of each query as it would apply to

the database state of Figure $3\mathrm{.}6.($Fundamentals of Database Systems, Ramez

Elmasri, Shamkant B$.$ Navathe$)$

$1)$ Retrieve the names of all employees in department $5$ who work more than $10$ hours per week on the ProductX project.

$2)$ Retrieve the names of all employees who work on every project.

$3)$ For each department, retrieve the department name and the average salary of all employees working in that department.

$4)$ Retrieve the names of all employees who do not work on any project.

$5)$ Retrieve the average salary of all female employees.