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Finding the Fourth Proportional to 678.72, 936.66 and 398.91

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Solution

The fourth proportional to 678.72, 936.66 and 398.91 is: 550.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.72 : 936.66 = 398.91 : x
  2. Step 2: Convert to fraction form
    678.72/936.66 = 398.91/x
  3. Step 3: Cross multiply
    678.72x = 936.66 × 398.91
  4. Step 4: Simplify right side
    678.72x = 373,643.04
  5. Step 5: Solve for x
    x = 373,643.04/678.72
  6. Step 6: Final answer
    x = 550.51

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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.