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Finding the Fourth Proportional to 678.88, 1,018.32 and 390.52

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Solution

The fourth proportional to 678.88, 1,018.32 and 390.52 is: 585.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.88 : 1,018.32 = 390.52 : x
  2. Step 2: Convert to fraction form
    678.88/1,018.32 = 390.52/x
  3. Step 3: Cross multiply
    678.88x = 1,018.32 × 390.52
  4. Step 4: Simplify right side
    678.88x = 397,674.33
  5. Step 5: Solve for x
    x = 397,674.33/678.88
  6. Step 6: Final answer
    x = 585.78

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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.