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Finding the Fourth Proportional to 720.72, 1,081.20 and 258.36

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Solution

The fourth proportional to 720.72, 1,081.20 and 258.36 is: 387.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.72 : 1,081.20 = 258.36 : x
  2. Step 2: Convert to fraction form
    720.72/1,081.20 = 258.36/x
  3. Step 3: Cross multiply
    720.72x = 1,081.20 × 258.36
  4. Step 4: Simplify right side
    720.72x = 279,338.83
  5. Step 5: Solve for x
    x = 279,338.83/720.72
  6. Step 6: Final answer
    x = 387.58

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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.