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Finding the Fourth Proportional to 678.87, 1,018.31 and 191.86

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Solution

The fourth proportional to 678.87, 1,018.31 and 191.86 is: 287.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.87 : 1,018.31 = 191.86 : x
  2. Step 2: Convert to fraction form
    678.87/1,018.31 = 191.86/x
  3. Step 3: Cross multiply
    678.87x = 1,018.31 × 191.86
  4. Step 4: Simplify right side
    678.87x = 195,369.45
  5. Step 5: Solve for x
    x = 195,369.45/678.87
  6. Step 6: Final answer
    x = 287.79

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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.