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Finding the Fourth Proportional to 393.40, 542.90 and 218.75

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Solution

The fourth proportional to 393.40, 542.90 and 218.75 is: 301.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    393.40 : 542.90 = 218.75 : x
  2. Step 2: Convert to fraction form
    393.40/542.90 = 218.75/x
  3. Step 3: Cross multiply
    393.40x = 542.90 × 218.75
  4. Step 4: Simplify right side
    393.40x = 118,761.28
  5. Step 5: Solve for x
    x = 118,761.28/393.40
  6. Step 6: Final answer
    x = 301.89

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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.