🔍 Key Concepts

• Relationship between ship speed and fuel consumption (often approximated as proportional to the cube of speed for exam purposes) • How to set up a fuel-consumption ratio using the known condition at 23 knots to find the unknown at 18 knots • Checking that the final answer is reasonable (slower speed should mean less tons per hour)

💭 Think About

• What mathematical relationship between speed and fuel burn rate is typically assumed in these exam questions? Is it linear, squared, or cubed? • How can you use the known case (5 tons/hour at 23 knots) to form a proportion that lets you solve for the unknown burn rate at 18 knots? • After you compute a number, how can you quickly compare it with the answer choices and rule out those that are clearly too high or too low?

✅ Before You Answer

• Be sure you apply the SAME exponent to both speeds when forming your ratio (for example, speed³ vs speed² vs speed¹) • Verify that your resulting tons per hour at 18 knots is less than 5 tons/hour but not unrealistically small • Double-check unit consistency: speed in knots, consumption in tons/hour, and your ratio should be dimensionless before you solve for the unknown