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Finding the Fourth Proportional to 978.90, 1,468.47 and 431.22

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Solution

The fourth proportional to 978.90, 1,468.47 and 431.22 is: 646.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.90 : 1,468.47 = 431.22 : x
  2. Step 2: Convert to fraction form
    978.90/1,468.47 = 431.22/x
  3. Step 3: Cross multiply
    978.90x = 1,468.47 × 431.22
  4. Step 4: Simplify right side
    978.90x = 633,233.63
  5. Step 5: Solve for x
    x = 633,233.63/978.90
  6. Step 6: Final answer
    x = 646.88

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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.