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Finding the Fourth Proportional to 420.98, 631.37 and 128.44

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Solution

The fourth proportional to 420.98, 631.37 and 128.44 is: 192.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.98 : 631.37 = 128.44 : x
  2. Step 2: Convert to fraction form
    420.98/631.37 = 128.44/x
  3. Step 3: Cross multiply
    420.98x = 631.37 × 128.44
  4. Step 4: Simplify right side
    420.98x = 81,091.91
  5. Step 5: Solve for x
    x = 81,091.91/420.98
  6. Step 6: Final answer
    x = 192.63

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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.