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 3…

Question

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

1. A. 250
2. B. 276
3. C. 280
4. D. 285 (Correct answer)

Correct Answer

Option D — 285

Detailed Solution & Explanation

The correct answer is 285.

Key Points

• A 30-day month beginning on a Sunday contains 5 Sundays and 25 other days.
• Total visitors = (5 × 510) + (25 × 240) = 2550 + 6000 = 8550.
• Average per day = 8550 ÷ 30 = 285.

Note

• Starting the month on a Sunday is what produces five Sundays rather than four — a detail these questions rely on.

Additional Information

• The 5 Sundays follow from the month beginning on a Sunday: Sundays then fall on the 1st, 8th, 15th, 22nd and 29th.
• General rule: a 30-day month contains four of each weekday plus two extra, and those two are the days on which the 1st and 2nd fall.
• Had the month begun on any other day, there would be only 4 Sundays and 26 other days, changing the average — so the starting day is essential data, not decoration.