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Finding the Fourth Proportional to 709.56, 979.20 and 390.51

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Solution

The fourth proportional to 709.56, 979.20 and 390.51 is: 538.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    709.56 : 979.20 = 390.51 : x
  2. Step 2: Convert to fraction form
    709.56/979.20 = 390.51/x
  3. Step 3: Cross multiply
    709.56x = 979.20 × 390.51
  4. Step 4: Simplify right side
    709.56x = 382,387.39
  5. Step 5: Solve for x
    x = 382,387.39/709.56
  6. Step 6: Final answer
    x = 538.91

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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.