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Finding the Fourth Proportional to 769.40, 1,061.79 and 420.09

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Solution

The fourth proportional to 769.40, 1,061.79 and 420.09 is: 579.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    769.40 : 1,061.79 = 420.09 : x
  2. Step 2: Convert to fraction form
    769.40/1,061.79 = 420.09/x
  3. Step 3: Cross multiply
    769.40x = 1,061.79 × 420.09
  4. Step 4: Simplify right side
    769.40x = 446,047.36
  5. Step 5: Solve for x
    x = 446,047.36/769.40
  6. Step 6: Final answer
    x = 579.73

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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.