Speed in m/s = 72 × 5/18 = 20 m/s. Distance = 20 × 25 = 500 m

When a boat moves in a river, its effective speed changes based on the stream direction. We use the formulas: Downstream speed = boat speed + stream speed, and Upstream speed = boat speed − stream speed.

Step 1: Calculate Downstream Speed

Downstream means the boat moves with the stream (both speeds add):

Step 2: Calculate Upstream Speed

Upstream means the boat moves against the stream (stream speed subtracts):

Step 3: Find the Ratio

The ratio of downstream to upstream speed is:

This simplifies to \(3:2\).

Answer: The ratio of downstream to upstream speed is \(3:2\) (Option B)

SP = 500 × 1.24 = Rs. 620. Wait, let me recalculate: 500 + (500 × 0.24) = 500 + 120 = 620. Correct answer should be B.

Let CP = 100. MP = 160. After 25% discount, SP = 160 × 0.75 = 120. Profit% = (120-100)/100 × 100 = 20%

Let initial salary = 100. After 15% increase = 115. After 10% decrease = 115 × 0.90 = 103.5. Net change = 3.5% increase

SI = 50000×12×2/100 = ₹12,000. CI = 50000(1.12)² - 50000 = ₹12,720. Difference = ₹720.

Rate = 1/20 + 1/30 - 1/60 = 3/60 + 2/60 - 1/60 = 4/60 = 1/15. Time = 15 minutes.

Distance = 150 + 250 = 400m. Speed = 400/20 = 20 m/s = 20×3.6 = 72 km/h.

Upstream speed = 24/6 = 4 km/h. Downstream speed = 24/3 = 8 km/h. Current = (8-4)/2 = 2 km/h.

MP = 80×1.25 = ₹100. SP = 100×0.9 = ₹90. Profit = 10/80 × 100 = 12.5%.