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Finding the Fourth Proportional to 678.90, 1,018.47 and 216.54

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Solution

The fourth proportional to 678.90, 1,018.47 and 216.54 is: 324.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.90 : 1,018.47 = 216.54 : x
  2. Step 2: Convert to fraction form
    678.90/1,018.47 = 216.54/x
  3. Step 3: Cross multiply
    678.90x = 1,018.47 × 216.54
  4. Step 4: Simplify right side
    678.90x = 220,539.49
  5. Step 5: Solve for x
    x = 220,539.49/678.90
  6. Step 6: Final answer
    x = 324.85

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.