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Finding the Fourth Proportional to 256.76, 384.87 and 128.51

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Solution

The fourth proportional to 256.76, 384.87 and 128.51 is: 192.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.76 : 384.87 = 128.51 : x
  2. Step 2: Convert to fraction form
    256.76/384.87 = 128.51/x
  3. Step 3: Cross multiply
    256.76x = 384.87 × 128.51
  4. Step 4: Simplify right side
    256.76x = 49,459.64
  5. Step 5: Solve for x
    x = 49,459.64/256.76
  6. Step 6: Final answer
    x = 192.63

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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.