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Finding the Fourth Proportional to 171.60, 257.20 and 86

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Solution

The fourth proportional to 171.60, 257.20 and 86 is: 128.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    171.60 : 257.20 = 86 : x
  2. Step 2: Convert to fraction form
    171.60/257.20 = 86/x
  3. Step 3: Cross multiply
    171.60x = 257.20 × 86
  4. Step 4: Simplify right side
    171.60x = 22,119.20
  5. Step 5: Solve for x
    x = 22,119.20/171.60
  6. Step 6: Final answer
    x = 128.90

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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.