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Finding the Fourth Proportional to 678.86, 1,018.60 and 313.76

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Solution

The fourth proportional to 678.86, 1,018.60 and 313.76 is: 470.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.86 : 1,018.60 = 313.76 : x
  2. Step 2: Convert to fraction form
    678.86/1,018.60 = 313.76/x
  3. Step 3: Cross multiply
    678.86x = 1,018.60 × 313.76
  4. Step 4: Simplify right side
    678.86x = 319,595.94
  5. Step 5: Solve for x
    x = 319,595.94/678.86
  6. Step 6: Final answer
    x = 470.78

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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.