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Finding the Fourth Proportional to 256.79, 385.15 and 74.20

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Solution

The fourth proportional to 256.79, 385.15 and 74.20 is: 111.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.79 : 385.15 = 74.20 : x
  2. Step 2: Convert to fraction form
    256.79/385.15 = 74.20/x
  3. Step 3: Cross multiply
    256.79x = 385.15 × 74.20
  4. Step 4: Simplify right side
    256.79x = 28,578.13
  5. Step 5: Solve for x
    x = 28,578.13/256.79
  6. Step 6: Final answer
    x = 111.29

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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.