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Finding the Fourth Proportional to 678.74, 936.64 and 398.92

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Solution

The fourth proportional to 678.74, 936.64 and 398.92 is: 550.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.74 : 936.64 = 398.92 : x
  2. Step 2: Convert to fraction form
    678.74/936.64 = 398.92/x
  3. Step 3: Cross multiply
    678.74x = 936.64 × 398.92
  4. Step 4: Simplify right side
    678.74x = 373,637.75
  5. Step 5: Solve for x
    x = 373,637.75/678.74
  6. Step 6: Final answer
    x = 550.49

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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.