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Finding the Fourth Proportional to 429.48, 642.30 and 421.80

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Solution

The fourth proportional to 429.48, 642.30 and 421.80 is: 630.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.48 : 642.30 = 421.80 : x
  2. Step 2: Convert to fraction form
    429.48/642.30 = 421.80/x
  3. Step 3: Cross multiply
    429.48x = 642.30 × 421.80
  4. Step 4: Simplify right side
    429.48x = 270,922.14
  5. Step 5: Solve for x
    x = 270,922.14/429.48
  6. Step 6: Final answer
    x = 630.81

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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.