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Finding the Fourth Proportional to 642.89, 887.13 and 421.49

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Solution

The fourth proportional to 642.89, 887.13 and 421.49 is: 581.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.89 : 887.13 = 421.49 : x
  2. Step 2: Convert to fraction form
    642.89/887.13 = 421.49/x
  3. Step 3: Cross multiply
    642.89x = 887.13 × 421.49
  4. Step 4: Simplify right side
    642.89x = 373,916.42
  5. Step 5: Solve for x
    x = 373,916.42/642.89
  6. Step 6: Final answer
    x = 581.62

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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.