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Finding the Fourth Proportional to 978.90, 1,468.71 and 431.88

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Solution

The fourth proportional to 978.90, 1,468.71 and 431.88 is: 647.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.90 : 1,468.71 = 431.88 : x
  2. Step 2: Convert to fraction form
    978.90/1,468.71 = 431.88/x
  3. Step 3: Cross multiply
    978.90x = 1,468.71 × 431.88
  4. Step 4: Simplify right side
    978.90x = 634,306.47
  5. Step 5: Solve for x
    x = 634,306.47/978.90
  6. Step 6: Final answer
    x = 647.98

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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.