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Finding the Third Proportional to 678.50 and 1,515

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Solution

The third proportional to 678.50 and 1,515 is: 3,382.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.50 : 1,515 = 1,515 : x
  2. Step 2: Convert to fraction form
    678.50/1,515 = 1,515/x
  3. Step 3: Cross multiply
    678.50x = 1,515 × 1,515
  4. Step 4: Simplify right side
    678.50x = 2,295,225
  5. Step 5: Solve for x
    x = 2,295,225/678.50
  6. Step 6: Final answer
    x = 3,382.79

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Why These Related Problems?

These problems maintain the same ratio (2.23) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.