A library has an average of 510 visitors on Sundays and 240 on other days. What is the average number of visitors per day in the month of June beginning with a Sunday?

If a month beings with Sunday then there are 5 Sundays in that month.
Total number of visitors comes on Sunday
= 510 × 5 = 2550
Total number of visitors come on other days
= 240 × 25 = 6000
∴ Average number of visitor per day
$$\eqalign{ & = \frac{{2550 + 6000}}{{30}} \cr & = \frac{{8550}}{{30}} \cr & = 285 \cr} $$