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Finding the Fourth Proportional to 489.78, 730.35 and 421.74

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Solution

The fourth proportional to 489.78, 730.35 and 421.74 is: 628.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    489.78 : 730.35 = 421.74 : x
  2. Step 2: Convert to fraction form
    489.78/730.35 = 421.74/x
  3. Step 3: Cross multiply
    489.78x = 730.35 × 421.74
  4. Step 4: Simplify right side
    489.78x = 308,017.81
  5. Step 5: Solve for x
    x = 308,017.81/489.78
  6. Step 6: Final answer
    x = 628.89

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.