A dolphin calf is born weighing 70 kg. Its weight doubles every 6 months. What will be its weight after 18 months?
Answer
560 kg
The correct answer is 560 kg — Therefore the calf will weigh 560 kg after 18 months.
Step-by-step solution
- Realise that weight doubles every 6 months, so over 18 months there are 18÷6=3 doubling intervals.
- Use the formula final = initial × 2ⁿ, where n is the number of intervals.
- Compute final = 70 × 2³.
- Calculate 2³ = 8 and 70 × 8 = 560.
- Therefore the calf will weigh 560 kg after 18 months.
Common mistake: Using 30 days per month to convert months into years incorrectly
Concept tested: Exponential growth calculation
Published · How this solution was prepared and checked
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