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Finding the Fourth Proportional to 678.64, 936.42 and 398.80

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Solution

The fourth proportional to 678.64, 936.42 and 398.80 is: 550.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.64 : 936.42 = 398.80 : x
  2. Step 2: Convert to fraction form
    678.64/936.42 = 398.80/x
  3. Step 3: Cross multiply
    678.64x = 936.42 × 398.80
  4. Step 4: Simplify right side
    678.64x = 373,444.30
  5. Step 5: Solve for x
    x = 373,444.30/678.64
  6. Step 6: Final answer
    x = 550.28

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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.