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Finding the Fourth Proportional to 393.60, 543.20 and 311.20

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Solution

The fourth proportional to 393.60, 543.20 and 311.20 is: 429.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    393.60 : 543.20 = 311.20 : x
  2. Step 2: Convert to fraction form
    393.60/543.20 = 311.20/x
  3. Step 3: Cross multiply
    393.60x = 543.20 × 311.20
  4. Step 4: Simplify right side
    393.60x = 169,043.84
  5. Step 5: Solve for x
    x = 169,043.84/393.60
  6. Step 6: Final answer
    x = 429.48

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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.