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Finding the Fourth Proportional to 256.80, 385.17 and 74.21

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Solution

The fourth proportional to 256.80, 385.17 and 74.21 is: 111.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.80 : 385.17 = 74.21 : x
  2. Step 2: Convert to fraction form
    256.80/385.17 = 74.21/x
  3. Step 3: Cross multiply
    256.80x = 385.17 × 74.21
  4. Step 4: Simplify right side
    256.80x = 28,583.73
  5. Step 5: Solve for x
    x = 28,583.73/256.80
  6. Step 6: Final answer
    x = 111.31

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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.