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Finding the Fourth Proportional to 720.70, 1,081.18 and 287.80

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Solution

The fourth proportional to 720.70, 1,081.18 and 287.80 is: 431.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.70 : 1,081.18 = 287.80 : x
  2. Step 2: Convert to fraction form
    720.70/1,081.18 = 287.80/x
  3. Step 3: Cross multiply
    720.70x = 1,081.18 × 287.80
  4. Step 4: Simplify right side
    720.70x = 311,163.60
  5. Step 5: Solve for x
    x = 311,163.60/720.70
  6. Step 6: Final answer
    x = 431.75

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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.