A library has an average of 510 visitors on Sunday and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is:

Correct answer: 285. A 30-day month beginning on Sunday has 5 Sundays and 25 other days. Total = 5 × 510 + 25 × 240 = 8550, and 8550 ÷ 30 = 285.

• 280: 280 is not the weighted average.
• 290: 290 is not the weighted average.
• 300: 300 is not the weighted average.