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Finding the Fourth Proportional to 769.86, 1,062.40 and 420.55

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Solution

The fourth proportional to 769.86, 1,062.40 and 420.55 is: 580.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    769.86 : 1,062.40 = 420.55 : x
  2. Step 2: Convert to fraction form
    769.86/1,062.40 = 420.55/x
  3. Step 3: Cross multiply
    769.86x = 1,062.40 × 420.55
  4. Step 4: Simplify right side
    769.86x = 446,792.32
  5. Step 5: Solve for x
    x = 446,792.32/769.86
  6. Step 6: Final answer
    x = 580.36

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.