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Finding the Fourth Proportional to 759.78, 1,139.67 and 419.94

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Solution

The fourth proportional to 759.78, 1,139.67 and 419.94 is: 629.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    759.78 : 1,139.67 = 419.94 : x
  2. Step 2: Convert to fraction form
    759.78/1,139.67 = 419.94/x
  3. Step 3: Cross multiply
    759.78x = 1,139.67 × 419.94
  4. Step 4: Simplify right side
    759.78x = 478,593.02
  5. Step 5: Solve for x
    x = 478,593.02/759.78
  6. Step 6: Final answer
    x = 629.91

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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.