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Finding the Fourth Proportional to 678.18, 935.78 and 398.54

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Solution

The fourth proportional to 678.18, 935.78 and 398.54 is: 549.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.18 : 935.78 = 398.54 : x
  2. Step 2: Convert to fraction form
    678.18/935.78 = 398.54/x
  3. Step 3: Cross multiply
    678.18x = 935.78 × 398.54
  4. Step 4: Simplify right side
    678.18x = 372,945.76
  5. Step 5: Solve for x
    x = 372,945.76/678.18
  6. Step 6: Final answer
    x = 549.92

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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.