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Finding the Fourth Proportional to 613.78, 920.67 and 431.99

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Solution

The fourth proportional to 613.78, 920.67 and 431.99 is: 647.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    613.78 : 920.67 = 431.99 : x
  2. Step 2: Convert to fraction form
    613.78/920.67 = 431.99/x
  3. Step 3: Cross multiply
    613.78x = 920.67 × 431.99
  4. Step 4: Simplify right side
    613.78x = 397,720.23
  5. Step 5: Solve for x
    x = 397,720.23/613.78
  6. Step 6: Final answer
    x = 647.99

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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.