Q77. Find the average number of red balls in B, D and E.

Question

Q77. Find the average number of red balls in B, D and E.

1. A. 355
2. B. 353
3. C. 350
4. D. 389 (Correct answer)
5. E. 386

Correct Answer

Option D — 389

Detailed Solution & Explanation

The correct answer is 389.

Key Points

• Table: Bag A — 240 balls (150 red, 90 blue); Bag B — 600 (399 red, 201 blue); Bag C — 470 (329 red, 141 blue); Bag D — 380 (228 red, 152 blue); Bag E — 750 (540 red, 210 blue).
• Each bag's red/blue split is found from the given red-minus-blue difference and percentage of red balls.
• Red balls in B, D and E are 399, 228 and 540 respectively.
• Average = (399 + 228 + 540) ÷ 3 = 1167 ÷ 3 = 389.
• the average = sum of values ÷ number of values.
• Add the three red-ball counts and divide by 3.

Exam Tip

• double-check which colour and which bags the question names; here it is red balls in B, D, E — picking the wrong colour or an extra bag is the most common slip in table-based averages.