A library has an average of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is:
Answer: D
If a month of 30 days begins with a Sunday, it will have 5 Sundays and 25 other days.
Total visitors on Sundays = 5 × 510 = 2550.
Total visitors on other days = 25 × 240 = 6000.
Total visitors in the month = 2550 + 6000 = 8550.
Average visitors per day = \(\frac{8550}{30} = 285\).