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Finding the Fourth Proportional to 257.72, 386.64 and 84.40

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Solution

The fourth proportional to 257.72, 386.64 and 84.40 is: 126.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.72 : 386.64 = 84.40 : x
  2. Step 2: Convert to fraction form
    257.72/386.64 = 84.40/x
  3. Step 3: Cross multiply
    257.72x = 386.64 × 84.40
  4. Step 4: Simplify right side
    257.72x = 32,632.42
  5. Step 5: Solve for x
    x = 32,632.42/257.72
  6. Step 6: Final answer
    x = 126.62

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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.