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Finding the Fourth Proportional to 257.72, 386.28 and 120.78

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Solution

The fourth proportional to 257.72, 386.28 and 120.78 is: 181.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.72 : 386.28 = 120.78 : x
  2. Step 2: Convert to fraction form
    257.72/386.28 = 120.78/x
  3. Step 3: Cross multiply
    257.72x = 386.28 × 120.78
  4. Step 4: Simplify right side
    257.72x = 46,654.90
  5. Step 5: Solve for x
    x = 46,654.90/257.72
  6. Step 6: Final answer
    x = 181.03

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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.