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Finding the Fourth Proportional to 678.58, 936.38 and 398.78

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Solution

The fourth proportional to 678.58, 936.38 and 398.78 is: 550.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.58 : 936.38 = 398.78 : x
  2. Step 2: Convert to fraction form
    678.58/936.38 = 398.78/x
  3. Step 3: Cross multiply
    678.58x = 936.38 × 398.78
  4. Step 4: Simplify right side
    678.58x = 373,409.62
  5. Step 5: Solve for x
    x = 373,409.62/678.58
  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.