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Finding the Fourth Proportional to 421.47, 632.21 and 128.97

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Solution

The fourth proportional to 421.47, 632.21 and 128.97 is: 193.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.47 : 632.21 = 128.97 : x
  2. Step 2: Convert to fraction form
    421.47/632.21 = 128.97/x
  3. Step 3: Cross multiply
    421.47x = 632.21 × 128.97
  4. Step 4: Simplify right side
    421.47x = 81,535.48
  5. Step 5: Solve for x
    x = 81,535.48/421.47
  6. Step 6: Final answer
    x = 193.46

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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.