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Finding the Fourth Proportional to 767.78, 1,150.71 and 420.90

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Solution

The fourth proportional to 767.78, 1,150.71 and 420.90 is: 630.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    767.78 : 1,150.71 = 420.90 : x
  2. Step 2: Convert to fraction form
    767.78/1,150.71 = 420.90/x
  3. Step 3: Cross multiply
    767.78x = 1,150.71 × 420.90
  4. Step 4: Simplify right side
    767.78x = 484,327.95
  5. Step 5: Solve for x
    x = 484,327.95/767.78
  6. Step 6: Final answer
    x = 630.82

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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.