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Finding the Fourth Proportional to 769.60, 1,061.36 and 638.40

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Solution

The fourth proportional to 769.60, 1,061.36 and 638.40 is: 880.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    769.60 : 1,061.36 = 638.40 : x
  2. Step 2: Convert to fraction form
    769.60/1,061.36 = 638.40/x
  3. Step 3: Cross multiply
    769.60x = 1,061.36 × 638.40
  4. Step 4: Simplify right side
    769.60x = 677,572.22
  5. Step 5: Solve for x
    x = 677,572.22/769.60
  6. Step 6: Final answer
    x = 880.42

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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.