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Finding the Fourth Proportional to 861.12, 1,292.16 and 428.16

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Solution

The fourth proportional to 861.12, 1,292.16 and 428.16 is: 642.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.12 : 1,292.16 = 428.16 : x
  2. Step 2: Convert to fraction form
    861.12/1,292.16 = 428.16/x
  3. Step 3: Cross multiply
    861.12x = 1,292.16 × 428.16
  4. Step 4: Simplify right side
    861.12x = 553,251.23
  5. Step 5: Solve for x
    x = 553,251.23/861.12
  6. Step 6: Final answer
    x = 642.48

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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.