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:

• A. 285
• B. 290
• C. 297
• D. 305

Hint:

Carefully count the number of specific days (e.g., Sundays) in the given month, especially when the starting day is specified. Avoid making assumptions about the number of weekend days if not explicitly stated.

Answer 1

The Correct Option is C

Step 1: A 30-day month starting on Sunday has Sundays on days 1, 8, 15, 22, 29, giving 5 Sundays and 25 other days.

Step 2: Instead of adding totals separately, apply the weighted average formula directly: \( \text{Average} = \frac{(5 \times 510) + (25 \times 240)}{30} \).

Step 3: Compute the weights as fractions of the month first: Sundays contribute \( \frac{5}{30} \times 510 = 85 \), and other days contribute \( \frac{25}{30} \times 240 = 200 \).

Step 4: Add the two weighted contributions: \( 85 + 200 = 285 \).
\[ \boxed{285} \]