Answer :

Since Mary worked 16 1/2 hours in 5 days

Then to find her average in a day, we will divide the total hours by the number of days.

[tex]\text{Ave}=\frac{16\frac{1}{2}}{5}[/tex]

We will change the mixed number 6 1/2 to an improper fraction

[tex]\begin{gathered} \text{Ave}=\frac{\frac{16\times2+1}{2}}{5} \\ \text{Ave}=\frac{\frac{33}{2}}{5} \\ \text{Ave}=\frac{33}{5\times2} \\ \text{Ave}=\frac{33}{10} \end{gathered}[/tex]

Then her average is 33/10 hour per day

We can change it to a mixed number

[tex]\text{Ave}\mathrm{}=3\frac{3}{10}[/tex]

Her average is 3 3/10 hours per day

Since 1 hour = 60 min, then change the fraction 3/10 to minutes

[tex]\frac{3}{10}\times60=3\times6=18\min [/tex]

Then her average is 3 hours 18 min per day