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Finding the Fourth Proportional to 656.43, 905.79 and 390.87

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Solution

The fourth proportional to 656.43, 905.79 and 390.87 is: 539.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    656.43 : 905.79 = 390.87 : x
  2. Step 2: Convert to fraction form
    656.43/905.79 = 390.87/x
  3. Step 3: Cross multiply
    656.43x = 905.79 × 390.87
  4. Step 4: Simplify right side
    656.43x = 354,046.14
  5. Step 5: Solve for x
    x = 354,046.14/656.43
  6. Step 6: Final answer
    x = 539.35

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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.