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Finding the Fourth Proportional to 393.44, 542.91 and 218.78

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Solution

The fourth proportional to 393.44, 542.91 and 218.78 is: 301.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    393.44 : 542.91 = 218.78 : x
  2. Step 2: Convert to fraction form
    393.44/542.91 = 218.78/x
  3. Step 3: Cross multiply
    393.44x = 542.91 × 218.78
  4. Step 4: Simplify right side
    393.44x = 118,777.85
  5. Step 5: Solve for x
    x = 118,777.85/393.44
  6. Step 6: Final answer
    x = 301.90

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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.