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Finding the Fourth Proportional to 642.39, 887.05 and 421.26

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Solution

The fourth proportional to 642.39, 887.05 and 421.26 is: 581.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.39 : 887.05 = 421.26 : x
  2. Step 2: Convert to fraction form
    642.39/887.05 = 421.26/x
  3. Step 3: Cross multiply
    642.39x = 887.05 × 421.26
  4. Step 4: Simplify right side
    642.39x = 373,678.68
  5. Step 5: Solve for x
    x = 373,678.68/642.39
  6. Step 6: Final answer
    x = 581.70

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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.