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Finding the Fourth Proportional to 642.20, 886.62 and 421.54

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Solution

The fourth proportional to 642.20, 886.62 and 421.54 is: 581.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.20 : 886.62 = 421.54 : x
  2. Step 2: Convert to fraction form
    642.20/886.62 = 421.54/x
  3. Step 3: Cross multiply
    642.20x = 886.62 × 421.54
  4. Step 4: Simplify right side
    642.20x = 373,740.89
  5. Step 5: Solve for x
    x = 373,740.89/642.20
  6. Step 6: Final answer
    x = 581.97

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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.