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Finding the Fourth Proportional to 393.70, 542.20 and 385.20

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Solution

The fourth proportional to 393.70, 542.20 and 385.20 is: 530.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    393.70 : 542.20 = 385.20 : x
  2. Step 2: Convert to fraction form
    393.70/542.20 = 385.20/x
  3. Step 3: Cross multiply
    393.70x = 542.20 × 385.20
  4. Step 4: Simplify right side
    393.70x = 208,855.44
  5. Step 5: Solve for x
    x = 208,855.44/393.70
  6. Step 6: Final answer
    x = 530.49

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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.