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Finding the Fourth Proportional to 978.70, 1,468.86 and 431.28

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Solution

The fourth proportional to 978.70, 1,468.86 and 431.28 is: 647.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.70 : 1,468.86 = 431.28 : x
  2. Step 2: Convert to fraction form
    978.70/1,468.86 = 431.28/x
  3. Step 3: Cross multiply
    978.70x = 1,468.86 × 431.28
  4. Step 4: Simplify right side
    978.70x = 633,489.94
  5. Step 5: Solve for x
    x = 633,489.94/978.70
  6. Step 6: Final answer
    x = 647.28

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.