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Finding the Fourth Proportional to 812.16, 1,218.78 and 427.68

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Solution

The fourth proportional to 812.16, 1,218.78 and 427.68 is: 641.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.16 : 1,218.78 = 427.68 : x
  2. Step 2: Convert to fraction form
    812.16/1,218.78 = 427.68/x
  3. Step 3: Cross multiply
    812.16x = 1,218.78 × 427.68
  4. Step 4: Simplify right side
    812.16x = 521,247.83
  5. Step 5: Solve for x
    x = 521,247.83/812.16
  6. Step 6: Final answer
    x = 641.80

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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.