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Finding the Fourth Proportional to 678.78, 936.81 and 399.08

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Solution

The fourth proportional to 678.78, 936.81 and 399.08 is: 550.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.78 : 936.81 = 399.08 : x
  2. Step 2: Convert to fraction form
    678.78/936.81 = 399.08/x
  3. Step 3: Cross multiply
    678.78x = 936.81 × 399.08
  4. Step 4: Simplify right side
    678.78x = 373,864.48
  5. Step 5: Solve for x
    x = 373,864.48/678.78
  6. Step 6: Final answer
    x = 550.79

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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.