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Finding the Fourth Proportional to 393.78, 590.20 and 220.40

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Solution

The fourth proportional to 393.78, 590.20 and 220.40 is: 330.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    393.78 : 590.20 = 220.40 : x
  2. Step 2: Convert to fraction form
    393.78/590.20 = 220.40/x
  3. Step 3: Cross multiply
    393.78x = 590.20 × 220.40
  4. Step 4: Simplify right side
    393.78x = 130,080.08
  5. Step 5: Solve for x
    x = 130,080.08/393.78
  6. Step 6: Final answer
    x = 330.34

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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.