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Finding the Fourth Proportional to 256.69, 385.05 and 85.69

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Solution

The fourth proportional to 256.69, 385.05 and 85.69 is: 128.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.69 : 385.05 = 85.69 : x
  2. Step 2: Convert to fraction form
    256.69/385.05 = 85.69/x
  3. Step 3: Cross multiply
    256.69x = 385.05 × 85.69
  4. Step 4: Simplify right side
    256.69x = 32,994.93
  5. Step 5: Solve for x
    x = 32,994.93/256.69
  6. Step 6: Final answer
    x = 128.54

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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.