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Finding the Fourth Proportional to 720.62, 1,078.91 and 390.37

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Solution

The fourth proportional to 720.62, 1,078.91 and 390.37 is: 584.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.62 : 1,078.91 = 390.37 : x
  2. Step 2: Convert to fraction form
    720.62/1,078.91 = 390.37/x
  3. Step 3: Cross multiply
    720.62x = 1,078.91 × 390.37
  4. Step 4: Simplify right side
    720.62x = 421,177.77
  5. Step 5: Solve for x
    x = 421,177.77/720.62
  6. Step 6: Final answer
    x = 584.47

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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.