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Finding the Fourth Proportional to 311.52, 430.80 and 309.60

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Solution

The fourth proportional to 311.52, 430.80 and 309.60 is: 428.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.52 : 430.80 = 309.60 : x
  2. Step 2: Convert to fraction form
    311.52/430.80 = 309.60/x
  3. Step 3: Cross multiply
    311.52x = 430.80 × 309.60
  4. Step 4: Simplify right side
    311.52x = 133,375.68
  5. Step 5: Solve for x
    x = 133,375.68/311.52
  6. Step 6: Final answer
    x = 428.14

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.