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Finding the Fourth Proportional to 812.08, 1,218.40 and 422.40

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Solution

The fourth proportional to 812.08, 1,218.40 and 422.40 is: 633.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.08 : 1,218.40 = 422.40 : x
  2. Step 2: Convert to fraction form
    812.08/1,218.40 = 422.40/x
  3. Step 3: Cross multiply
    812.08x = 1,218.40 × 422.40
  4. Step 4: Simplify right side
    812.08x = 514,652.16
  5. Step 5: Solve for x
    x = 514,652.16/812.08
  6. Step 6: Final answer
    x = 633.75

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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.