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Finding the Fourth Proportional to 257.76, 386.40 and 209.28

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Solution

The fourth proportional to 257.76, 386.40 and 209.28 is: 313.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.76 : 386.40 = 209.28 : x
  2. Step 2: Convert to fraction form
    257.76/386.40 = 209.28/x
  3. Step 3: Cross multiply
    257.76x = 386.40 × 209.28
  4. Step 4: Simplify right side
    257.76x = 80,865.79
  5. Step 5: Solve for x
    x = 80,865.79/257.76
  6. Step 6: Final answer
    x = 313.73

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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.