Question $3(15$ points$)$ RUSHNOT Ltd specializes in the production of doorknob and allocates manufacturing overheads $($both fixed and variable$)$ using manufacturing labour hours. For March $2025,$ the company budgeted to produce $1,500$ units of doorknobs with a standard of $2$ manufacturing labour hours per unit of doorknob. Total fixed overheads were budgeted at $\backslash (\backslash$$ $60,000\backslash )$; and variable overheads per manufacturing labour hour were budgeted at $\backslash (\backslash$$ $15\backslash ).$ During March, RUSHNOT produced $1,600$ units of doorknob and incurred the following overhead costs: $-$ Variable manufacturing overheads: $\backslash (\backslash$$ $47,040\backslash )-$ Fixed manufacturing overheads: $\backslash (\backslash$$ $70,560\backslash )$ The actual labour hours used during March were $3,360$ hours. Required: Calculate $1)$ the fixed manufacturing overhead rate variance, $[5$ marks$]2)$ the production volume variance, and $[5$ marks$]3)$ the fixed manufacturing over or under$-$allocated overhead $[5$ marks$]$