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Finding the Fourth Proportional to 812.94, 1,220.49 and 428.46

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Solution

The fourth proportional to 812.94, 1,220.49 and 428.46 is: 643.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.94 : 1,220.49 = 428.46 : x
  2. Step 2: Convert to fraction form
    812.94/1,220.49 = 428.46/x
  3. Step 3: Cross multiply
    812.94x = 1,220.49 × 428.46
  4. Step 4: Simplify right side
    812.94x = 522,931.15
  5. Step 5: Solve for x
    x = 522,931.15/812.94
  6. Step 6: Final answer
    x = 643.26

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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.