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Finding the Fourth Proportional to 171.78, 257.64 and 80.47

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Solution

The fourth proportional to 171.78, 257.64 and 80.47 is: 120.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    171.78 : 257.64 = 80.47 : x
  2. Step 2: Convert to fraction form
    171.78/257.64 = 80.47/x
  3. Step 3: Cross multiply
    171.78x = 257.64 × 80.47
  4. Step 4: Simplify right side
    171.78x = 20,731.00
  5. Step 5: Solve for x
    x = 20,731.00/171.78
  6. Step 6: Final answer
    x = 120.68

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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.