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Finding the Fourth Proportional to 812.55, 1,218.38 and 421.58

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Solution

The fourth proportional to 812.55, 1,218.38 and 421.58 is: 632.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.55 : 1,218.38 = 421.58 : x
  2. Step 2: Convert to fraction form
    812.55/1,218.38 = 421.58/x
  3. Step 3: Cross multiply
    812.55x = 1,218.38 × 421.58
  4. Step 4: Simplify right side
    812.55x = 513,640.54
  5. Step 5: Solve for x
    x = 513,640.54/812.55
  6. Step 6: Final answer
    x = 632.14

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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.