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Finding the Fourth Proportional to 978.67, 1,468.48 and 430.78

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Solution

The fourth proportional to 978.67, 1,468.48 and 430.78 is: 646.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.67 : 1,468.48 = 430.78 : x
  2. Step 2: Convert to fraction form
    978.67/1,468.48 = 430.78/x
  3. Step 3: Cross multiply
    978.67x = 1,468.48 × 430.78
  4. Step 4: Simplify right side
    978.67x = 632,591.81
  5. Step 5: Solve for x
    x = 632,591.81/978.67
  6. Step 6: Final answer
    x = 646.38

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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.