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Finding the Fourth Proportional to 421.12, 631.41 and 128.52

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Solution

The fourth proportional to 421.12, 631.41 and 128.52 is: 192.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.12 : 631.41 = 128.52 : x
  2. Step 2: Convert to fraction form
    421.12/631.41 = 128.52/x
  3. Step 3: Cross multiply
    421.12x = 631.41 × 128.52
  4. Step 4: Simplify right side
    421.12x = 81,148.06
  5. Step 5: Solve for x
    x = 81,148.06/421.12
  6. Step 6: Final answer
    x = 192.70

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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.