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Finding the Fourth Proportional to 420.12, 630.20 and 142.47

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Solution

The fourth proportional to 420.12, 630.20 and 142.47 is: 213.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.12 : 630.20 = 142.47 : x
  2. Step 2: Convert to fraction form
    420.12/630.20 = 142.47/x
  3. Step 3: Cross multiply
    420.12x = 630.20 × 142.47
  4. Step 4: Simplify right side
    420.12x = 89,784.95
  5. Step 5: Solve for x
    x = 89,784.95/420.12
  6. Step 6: Final answer
    x = 213.71

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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.