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Finding the Third Proportional to 390.75 and 658.50

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Solution

The third proportional to 390.75 and 658.50 is: 1,109.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.75 : 658.50 = 658.50 : x
  2. Step 2: Convert to fraction form
    390.75/658.50 = 658.50/x
  3. Step 3: Cross multiply
    390.75x = 658.50 × 658.50
  4. Step 4: Simplify right side
    390.75x = 433,622.25
  5. Step 5: Solve for x
    x = 433,622.25/390.75
  6. Step 6: Final answer
    x = 1,109.72

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Why These Related Problems?

These problems maintain the same ratio (1.69) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.