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Finding the Fourth Proportional to 761.49, 1,139.80 and 395.78

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Solution

The fourth proportional to 761.49, 1,139.80 and 395.78 is: 592.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    761.49 : 1,139.80 = 395.78 : x
  2. Step 2: Convert to fraction form
    761.49/1,139.80 = 395.78/x
  3. Step 3: Cross multiply
    761.49x = 1,139.80 × 395.78
  4. Step 4: Simplify right side
    761.49x = 451,102.37
  5. Step 5: Solve for x
    x = 451,102.37/761.49
  6. Step 6: Final answer
    x = 592.39

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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.