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Finding the Fourth Proportional to 256.76, 385.18 and 85.80

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Solution

The fourth proportional to 256.76, 385.18 and 85.80 is: 128.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.76 : 385.18 = 85.80 : x
  2. Step 2: Convert to fraction form
    256.76/385.18 = 85.80/x
  3. Step 3: Cross multiply
    256.76x = 385.18 × 85.80
  4. Step 4: Simplify right side
    256.76x = 33,048.44
  5. Step 5: Solve for x
    x = 33,048.44/256.76
  6. Step 6: Final answer
    x = 128.71

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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.