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Finding the Fourth Proportional to 709.99, 979.78 and 399.49

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Solution

The fourth proportional to 709.99, 979.78 and 399.49 is: 551.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    709.99 : 979.78 = 399.49 : x
  2. Step 2: Convert to fraction form
    709.99/979.78 = 399.49/x
  3. Step 3: Cross multiply
    709.99x = 979.78 × 399.49
  4. Step 4: Simplify right side
    709.99x = 391,412.31
  5. Step 5: Solve for x
    x = 391,412.31/709.99
  6. Step 6: Final answer
    x = 551.29

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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.