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Finding the Fourth Proportional to 720.65, 1,080.30 and 391.11

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Solution

The fourth proportional to 720.65, 1,080.30 and 391.11 is: 586.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.65 : 1,080.30 = 391.11 : x
  2. Step 2: Convert to fraction form
    720.65/1,080.30 = 391.11/x
  3. Step 3: Cross multiply
    720.65x = 1,080.30 × 391.11
  4. Step 4: Simplify right side
    720.65x = 422,510.73
  5. Step 5: Solve for x
    x = 422,510.73/720.65
  6. Step 6: Final answer
    x = 586.29

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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.