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Finding the Fourth Proportional to 420.48, 630.78 and 127.92

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Solution

The fourth proportional to 420.48, 630.78 and 127.92 is: 191.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.48 : 630.78 = 127.92 : x
  2. Step 2: Convert to fraction form
    420.48/630.78 = 127.92/x
  3. Step 3: Cross multiply
    420.48x = 630.78 × 127.92
  4. Step 4: Simplify right side
    420.48x = 80,689.38
  5. Step 5: Solve for x
    x = 80,689.38/420.48
  6. Step 6: Final answer
    x = 191.90

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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.