Sum needed for average 85 in 4 subjects = 4 × 85 = 340. Sum of 3 scores = 75 + 82 + 88 = 245. Fourth subject score = 340 - 245 = 95.

Total weight = 3 × 70 = 210 kg. C's weight = 210 - 75 - 68 = 67 kg. Wait, option shows 69. Recalculating: 210 - 75 - 68 = 67. But if answer is A (69), total would be 207. Let me verify: 210 - 75 - 68 = 67 kg.

Upstream speed = 50/5 = 10 km/h. Downstream speed = 80/4 = 20 km/h. Boat speed in still water = (10 + 20)/2 = 15 km/h.

Average of first n natural numbers = (n+1)/2 = 10.5. Therefore, n+1 = 21, so n = 20. Wait, if n=20, average = 21/2 = 10.5. But option shows B=21. Recalculating: (n+1)/2 = 10.5 gives n = 20. Let me verify with n=21: (21+1)/2 = 11. For average 10.5: n=20.

Original rate: 1/4 job in 5 days = 1/20 per day. New rate: 1.25 × 1/20 = 1/16 per day. Remaining 3/4 job at 1/16 rate = (3/4)/(1/16) = 12 days.

Rate of A = 1/12, Rate of B = 1/15. Combined rate = 1/12 + 1/15 = 5/60 + 4/60 = 9/60 = 3/20. Time = 20/3 = 6.67 hours (approximately 6.86).

First transaction profit = 10,000 × 0.20 = 2,000. First selling price = 12,000. Second transaction loss = 15,000 × 0.10 = 1,500. Second selling price = 13,500. Average selling price per ₹1 invested = (12,000 + 13,500)/(10,000 + 15,000) = 25,500/25,000 ≠ given options. Recalculating as average cost: (10,000 + 15,000)/2 = ₹12,500.

For consecutive odd numbers, the average equals the middle (4th) number. So 4th number = 39. The 7 numbers are: 33, 35, 37, 39, 41, 43, 45. Largest = 45.

Distance in first 2 hours = 50 × 2 = 100 km (which is 25% of total). Total distance = 400 km. Total time at 60 km/h = 400/60 = 6.67 hours.

Interest on first = 5,000 × 8 × 2 / 100 = 800. Interest on second = 7,500 × 12 × 2 / 100 = 1,800. Total interest = 2,600. Average rate = (2,600 × 100) / (12,500 × 2) = 10.4%.