Answer : Option C

Explanation :

in a month of 30 days beginning with a Sunday, there will be 4 complete weeks and
another two days which will be Sunday and Monday
Hence there will be 5 Sundays and 25 other days in a month of 30 days beginning with
a Sunday
$MF#%\begin{align}
&\text{Average visitors on Sundays = }510\\\\
&\text{Total visitors of 5 Sundays = }510 \times 5\\\\\\\\\\\\
&\text{Average visitors on other days = }240\\\\
&\text{Total visitors of other 25 days = }240 \times 25\\\\\\\\\\\\
&\text{Total visitors = }\left( 510 \times 5 \right)+\left( 240 \times 25\right)\\\\
&\text{Total days= }30\\\\
&\text{Average number of visitors per day = }\dfrac{\left( 510 \times 5 \right)+\left( 240 \times 25\right)}{30}\\\\
&= \dfrac{\left( 51 \times 5 \right)+\left( 24 \times 25\right)}{3} = \left( 17\times 5 \right)+\left( 8\times 25\right) = 85+200=285 \\\\
\end{align} $MF#%