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Finding the Fourth Proportional to 720.85, 1,081.28 and 309.64

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Solution

The fourth proportional to 720.85, 1,081.28 and 309.64 is: 464.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.85 : 1,081.28 = 309.64 : x
  2. Step 2: Convert to fraction form
    720.85/1,081.28 = 309.64/x
  3. Step 3: Cross multiply
    720.85x = 1,081.28 × 309.64
  4. Step 4: Simplify right side
    720.85x = 334,807.54
  5. Step 5: Solve for x
    x = 334,807.54/720.85
  6. Step 6: Final answer
    x = 464.46

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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.