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Finding the Fourth Proportional to 291.20, 434.96 and 209.40

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Solution

The fourth proportional to 291.20, 434.96 and 209.40 is: 312.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    291.20 : 434.96 = 209.40 : x
  2. Step 2: Convert to fraction form
    291.20/434.96 = 209.40/x
  3. Step 3: Cross multiply
    291.20x = 434.96 × 209.40
  4. Step 4: Simplify right side
    291.20x = 91,080.62
  5. Step 5: Solve for x
    x = 91,080.62/291.20
  6. Step 6: Final answer
    x = 312.78

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.