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Finding the Fourth Proportional to 643.10, 887.42 and 421.67

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Solution

The fourth proportional to 643.10, 887.42 and 421.67 is: 581.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.10 : 887.42 = 421.67 : x
  2. Step 2: Convert to fraction form
    643.10/887.42 = 421.67/x
  3. Step 3: Cross multiply
    643.10x = 887.42 × 421.67
  4. Step 4: Simplify right side
    643.10x = 374,201.66
  5. Step 5: Solve for x
    x = 374,201.66/643.10
  6. Step 6: Final answer
    x = 581.88

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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.