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Finding the Fourth Proportional to 715.20, 1,072.08 and 390.84

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Solution

The fourth proportional to 715.20, 1,072.08 and 390.84 is: 585.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.20 : 1,072.08 = 390.84 : x
  2. Step 2: Convert to fraction form
    715.20/1,072.08 = 390.84/x
  3. Step 3: Cross multiply
    715.20x = 1,072.08 × 390.84
  4. Step 4: Simplify right side
    715.20x = 419,011.75
  5. Step 5: Solve for x
    x = 419,011.75/715.20
  6. Step 6: Final answer
    x = 585.87

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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.