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Finding the Fourth Proportional to 398.82, 551.08 and 312.15

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Solution

The fourth proportional to 398.82, 551.08 and 312.15 is: 431.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    398.82 : 551.08 = 312.15 : x
  2. Step 2: Convert to fraction form
    398.82/551.08 = 312.15/x
  3. Step 3: Cross multiply
    398.82x = 551.08 × 312.15
  4. Step 4: Simplify right side
    398.82x = 172,016.87
  5. Step 5: Solve for x
    x = 172,016.87/398.82
  6. Step 6: Final answer
    x = 431.32

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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.