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Finding the Fourth Proportional to 420.59, 630.88 and 128.09

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Solution

The fourth proportional to 420.59, 630.88 and 128.09 is: 192.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.59 : 630.88 = 128.09 : x
  2. Step 2: Convert to fraction form
    420.59/630.88 = 128.09/x
  3. Step 3: Cross multiply
    420.59x = 630.88 × 128.09
  4. Step 4: Simplify right side
    420.59x = 80,809.42
  5. Step 5: Solve for x
    x = 80,809.42/420.59
  6. Step 6: Final answer
    x = 192.13

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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.