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Finding the Fourth Proportional to 642.11, 885.78 and 421.07

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Solution

The fourth proportional to 642.11, 885.78 and 421.07 is: 580.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.11 : 885.78 = 421.07 : x
  2. Step 2: Convert to fraction form
    642.11/885.78 = 421.07/x
  3. Step 3: Cross multiply
    642.11x = 885.78 × 421.07
  4. Step 4: Simplify right side
    642.11x = 372,970.96
  5. Step 5: Solve for x
    x = 372,970.96/642.11
  6. Step 6: Final answer
    x = 580.86

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.