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Finding the Fourth Proportional to 709.86, 979.39 and 485.80

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Solution

The fourth proportional to 709.86, 979.39 and 485.80 is: 670.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    709.86 : 979.39 = 485.80 : x
  2. Step 2: Convert to fraction form
    709.86/979.39 = 485.80/x
  3. Step 3: Cross multiply
    709.86x = 979.39 × 485.80
  4. Step 4: Simplify right side
    709.86x = 475,785.82
  5. Step 5: Solve for x
    x = 475,785.82/709.86
  6. Step 6: Final answer
    x = 670.25

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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.