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Finding the Fourth Proportional to 720.31, 1,080.97 and 391.91

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Solution

The fourth proportional to 720.31, 1,080.97 and 391.91 is: 588.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.31 : 1,080.97 = 391.91 : x
  2. Step 2: Convert to fraction form
    720.31/1,080.97 = 391.91/x
  3. Step 3: Cross multiply
    720.31x = 1,080.97 × 391.91
  4. Step 4: Simplify right side
    720.31x = 423,646.79
  5. Step 5: Solve for x
    x = 423,646.79/720.31
  6. Step 6: Final answer
    x = 588.15

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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.