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Finding the Fourth Proportional to 420.73, 631.09 and 128.23

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Solution

The fourth proportional to 420.73, 631.09 and 128.23 is: 192.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.73 : 631.09 = 128.23 : x
  2. Step 2: Convert to fraction form
    420.73/631.09 = 128.23/x
  3. Step 3: Cross multiply
    420.73x = 631.09 × 128.23
  4. Step 4: Simplify right side
    420.73x = 80,921.19
  5. Step 5: Solve for x
    x = 80,921.19/420.73
  6. Step 6: Final answer
    x = 192.34

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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.