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Finding the Fourth Proportional to 287.39, 431.09 and 81.93

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Solution

The fourth proportional to 287.39, 431.09 and 81.93 is: 122.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    287.39 : 431.09 = 81.93 : x
  2. Step 2: Convert to fraction form
    287.39/431.09 = 81.93/x
  3. Step 3: Cross multiply
    287.39x = 431.09 × 81.93
  4. Step 4: Simplify right side
    287.39x = 35,319.20
  5. Step 5: Solve for x
    x = 35,319.20/287.39
  6. Step 6: Final answer
    x = 122.90

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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.