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Finding the Fourth Proportional to 861.04, 1,291.02 and 428.68

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Solution

The fourth proportional to 861.04, 1,291.02 and 428.68 is: 642.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.04 : 1,291.02 = 428.68 : x
  2. Step 2: Convert to fraction form
    861.04/1,291.02 = 428.68/x
  3. Step 3: Cross multiply
    861.04x = 1,291.02 × 428.68
  4. Step 4: Simplify right side
    861.04x = 553,434.45
  5. Step 5: Solve for x
    x = 553,434.45/861.04
  6. Step 6: Final answer
    x = 642.75

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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.