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Finding the Fourth Proportional to 429.70, 644.55 and 421.60

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Solution

The fourth proportional to 429.70, 644.55 and 421.60 is: 632.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.70 : 644.55 = 421.60 : x
  2. Step 2: Convert to fraction form
    429.70/644.55 = 421.60/x
  3. Step 3: Cross multiply
    429.70x = 644.55 × 421.60
  4. Step 4: Simplify right side
    429.70x = 271,742.28
  5. Step 5: Solve for x
    x = 271,742.28/429.70
  6. Step 6: Final answer
    x = 632.40

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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.