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Finding the Fourth Proportional to 621.74, 931.97 and 390.79

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Solution

The fourth proportional to 621.74, 931.97 and 390.79 is: 585.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    621.74 : 931.97 = 390.79 : x
  2. Step 2: Convert to fraction form
    621.74/931.97 = 390.79/x
  3. Step 3: Cross multiply
    621.74x = 931.97 × 390.79
  4. Step 4: Simplify right side
    621.74x = 364,204.56
  5. Step 5: Solve for x
    x = 364,204.56/621.74
  6. Step 6: Final answer
    x = 585.78

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.