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Finding the Fourth Proportional to 861.84, 1,291.86 and 428.04

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Solution

The fourth proportional to 861.84, 1,291.86 and 428.04 is: 641.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.84 : 1,291.86 = 428.04 : x
  2. Step 2: Convert to fraction form
    861.84/1,291.86 = 428.04/x
  3. Step 3: Cross multiply
    861.84x = 1,291.86 × 428.04
  4. Step 4: Simplify right side
    861.84x = 552,967.75
  5. Step 5: Solve for x
    x = 552,967.75/861.84
  6. Step 6: Final answer
    x = 641.61

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.