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Finding the Fourth Proportional to 720.36, 1,080.72 and 391.15

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Solution

The fourth proportional to 720.36, 1,080.72 and 391.15 is: 586.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.36 : 1,080.72 = 391.15 : x
  2. Step 2: Convert to fraction form
    720.36/1,080.72 = 391.15/x
  3. Step 3: Cross multiply
    720.36x = 1,080.72 × 391.15
  4. Step 4: Simplify right side
    720.36x = 422,723.63
  5. Step 5: Solve for x
    x = 422,723.63/720.36
  6. Step 6: Final answer
    x = 586.82

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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.