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Finding the Fourth Proportional to 421.72, 632.64 and 129.21

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Solution

The fourth proportional to 421.72, 632.64 and 129.21 is: 193.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.72 : 632.64 = 129.21 : x
  2. Step 2: Convert to fraction form
    421.72/632.64 = 129.21/x
  3. Step 3: Cross multiply
    421.72x = 632.64 × 129.21
  4. Step 4: Simplify right side
    421.72x = 81,742.55
  5. Step 5: Solve for x
    x = 81,742.55/421.72
  6. Step 6: Final answer
    x = 193.83

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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.