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Finding the Fourth Proportional to 678.20, 935.89 and 398.43

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Solution

The fourth proportional to 678.20, 935.89 and 398.43 is: 549.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.20 : 935.89 = 398.43 : x
  2. Step 2: Convert to fraction form
    678.20/935.89 = 398.43/x
  3. Step 3: Cross multiply
    678.20x = 935.89 × 398.43
  4. Step 4: Simplify right side
    678.20x = 372,886.65
  5. Step 5: Solve for x
    x = 372,886.65/678.20
  6. Step 6: Final answer
    x = 549.82

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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.