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Finding the Fourth Proportional to 398.20, 549.40 and 311.12

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Solution

The fourth proportional to 398.20, 549.40 and 311.12 is: 429.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    398.20 : 549.40 = 311.12 : x
  2. Step 2: Convert to fraction form
    398.20/549.40 = 311.12/x
  3. Step 3: Cross multiply
    398.20x = 549.40 × 311.12
  4. Step 4: Simplify right side
    398.20x = 170,929.33
  5. Step 5: Solve for x
    x = 170,929.33/398.20
  6. Step 6: Final answer
    x = 429.25

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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.