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Finding the Third Proportional to 390.21 and 579.38

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Solution

The third proportional to 390.21 and 579.38 is: 860.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.21 : 579.38 = 579.38 : x
  2. Step 2: Convert to fraction form
    390.21/579.38 = 579.38/x
  3. Step 3: Cross multiply
    390.21x = 579.38 × 579.38
  4. Step 4: Simplify right side
    390.21x = 335,680.48
  5. Step 5: Solve for x
    x = 335,680.48/390.21
  6. Step 6: Final answer
    x = 860.26

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Why These Related Problems?

These problems maintain the same ratio (1.48) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.