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Finding the Fourth Proportional to 421.78, 632.48 and 129.18

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Solution

The fourth proportional to 421.78, 632.48 and 129.18 is: 193.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.78 : 632.48 = 129.18 : x
  2. Step 2: Convert to fraction form
    421.78/632.48 = 129.18/x
  3. Step 3: Cross multiply
    421.78x = 632.48 × 129.18
  4. Step 4: Simplify right side
    421.78x = 81,703.77
  5. Step 5: Solve for x
    x = 81,703.77/421.78
  6. Step 6: Final answer
    x = 193.71

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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.