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Finding the Third Proportional to 390.88 and 639.13

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Solution

The third proportional to 390.88 and 639.13 is: 1,045.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.88 : 639.13 = 639.13 : x
  2. Step 2: Convert to fraction form
    390.88/639.13 = 639.13/x
  3. Step 3: Cross multiply
    390.88x = 639.13 × 639.13
  4. Step 4: Simplify right side
    390.88x = 408,480.77
  5. Step 5: Solve for x
    x = 408,480.77/390.88
  6. Step 6: Final answer
    x = 1,045.04

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Why These Related Problems?

These problems maintain the same ratio (1.64) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.