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Finding the Fourth Proportional to 626.39, 864.30 and 390.40

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Solution

The fourth proportional to 626.39, 864.30 and 390.40 is: 538.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    626.39 : 864.30 = 390.40 : x
  2. Step 2: Convert to fraction form
    626.39/864.30 = 390.40/x
  3. Step 3: Cross multiply
    626.39x = 864.30 × 390.40
  4. Step 4: Simplify right side
    626.39x = 337,422.72
  5. Step 5: Solve for x
    x = 337,422.72/626.39
  6. Step 6: Final answer
    x = 538.68

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.