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Finding the Fourth Proportional to 678.49, 935.92 and 398.66

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Solution

The fourth proportional to 678.49, 935.92 and 398.66 is: 549.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.49 : 935.92 = 398.66 : x
  2. Step 2: Convert to fraction form
    678.49/935.92 = 398.66/x
  3. Step 3: Cross multiply
    678.49x = 935.92 × 398.66
  4. Step 4: Simplify right side
    678.49x = 373,115.21
  5. Step 5: Solve for x
    x = 373,115.21/678.49
  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.