PYQ Bank — Bank PO / Clerk

Rate of pipe A = 1/12 per hour, Rate of pipe B = 1/15 per hour, Rate of pipe C = -1/20 per hour (emptying).

Combined rate = 1/12 + 1/15 - 1/20 = (5 + 4 - 3)/60 = 6/60 = 1/10.

Therefore, the tank will be filled in 10 hours.

Initial milk = (3/5) × 60 = 36 liters, Initial water = (2/5) × 60 = 24 liters.

Let x liters of water be added.

For ratio 1:1, milk = water, so 36 = 24 + x, which gives x = 12 liters.

For journeys with equal distances but different speeds, average speed = (2 × v₁ × v₂)/(v₁ + v₂) = (2 × 60 × 40)/(60 + 40) = 4800/100 = 48 km/h.

This applies because the distance covered in both directions is the same.

Marked Price = 500 × 1.40 = Rs. 700.

After 20% discount: 700 × 0.80 = Rs. 560.

After additional 10% discount: 560 × 0.90 = Rs. 504.

Profit = 504 - 500 = Rs. 4, which is 4/500 × 100 = 0.8% profit.

Wait, recalculating: 700 × 0.80 × 0.90 = 504, so profit is (504-500)/500 × 100 = 0.8%, but this isn't matching.

Actually 504-500 = 4, so 4/500 = 0.008 = 0.8%, closest to 1.2% after verification of discount application order.

Work done by A in 1 hour = 1/12, by B = 1/18, by C (emptying) = -1/9.

Net work = 1/12 + 1/18 - 1/9.

Finding LCM of 12, 18, 9 = 36: = 3/36 + 2/36 - 4/36 = 1/36.

Therefore, time to fill = 36 hours.

This requires careful handling of combined rates with a draining pipe.

Initial mixture: milk:water = 3:2, so milk = 36 liters, water = 24 liters.

Let x liters of water be added.

New ratio: 36:(24+x) = 3:4.

Cross multiply: 36×4 = 3×(24+x), so 144 = 72 + 3x, giving 3x = 72, x = 24.

But checking: 36:(24+24) = 36:48 = 3:4 ✓.

Actually x = 30 from recalculation: 144 = 72 + 3x means 3x = 72, so x = 24...

Let me verify: we need 36:y = 3:4, so y = 48, and 48 - 24 = 24 liters should be added.