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Finding the Fourth Proportional to 679.86, 1,019.07 and 643.86

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Solution

The fourth proportional to 679.86, 1,019.07 and 643.86 is: 965.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.86 : 1,019.07 = 643.86 : x
  2. Step 2: Convert to fraction form
    679.86/1,019.07 = 643.86/x
  3. Step 3: Cross multiply
    679.86x = 1,019.07 × 643.86
  4. Step 4: Simplify right side
    679.86x = 656,138.41
  5. Step 5: Solve for x
    x = 656,138.41/679.86
  6. Step 6: Final answer
    x = 965.11

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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.