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Finding the Fourth Proportional to 256.21, 353.57 and 139.78

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Solution

The fourth proportional to 256.21, 353.57 and 139.78 is: 192.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.21 : 353.57 = 139.78 : x
  2. Step 2: Convert to fraction form
    256.21/353.57 = 139.78/x
  3. Step 3: Cross multiply
    256.21x = 353.57 × 139.78
  4. Step 4: Simplify right side
    256.21x = 49,420.25
  5. Step 5: Solve for x
    x = 49,420.25/256.21
  6. Step 6: Final answer
    x = 192.89

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.