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Finding the Fourth Proportional to 679.67, 1,019.81 and 391.11

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Solution

The fourth proportional to 679.67, 1,019.81 and 391.11 is: 586.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.67 : 1,019.81 = 391.11 : x
  2. Step 2: Convert to fraction form
    679.67/1,019.81 = 391.11/x
  3. Step 3: Cross multiply
    679.67x = 1,019.81 × 391.11
  4. Step 4: Simplify right side
    679.67x = 398,857.89
  5. Step 5: Solve for x
    x = 398,857.89/679.67
  6. Step 6: Final answer
    x = 586.84

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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.