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Finding the Fourth Proportional to 679.86, 1,020.20 and 419.85

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Solution

The fourth proportional to 679.86, 1,020.20 and 419.85 is: 630.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.86 : 1,020.20 = 419.85 : x
  2. Step 2: Convert to fraction form
    679.86/1,020.20 = 419.85/x
  3. Step 3: Cross multiply
    679.86x = 1,020.20 × 419.85
  4. Step 4: Simplify right side
    679.86x = 428,328.87
  5. Step 5: Solve for x
    x = 428,328.87/679.86
  6. Step 6: Final answer
    x = 630.03

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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.