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Finding the Fourth Proportional to 805.22, 1,205.90 and 689

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Solution

The fourth proportional to 805.22, 1,205.90 and 689 is: 1,031.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    805.22 : 1,205.90 = 689 : x
  2. Step 2: Convert to fraction form
    805.22/1,205.90 = 689/x
  3. Step 3: Cross multiply
    805.22x = 1,205.90 × 689
  4. Step 4: Simplify right side
    805.22x = 830,865.10
  5. Step 5: Solve for x
    x = 830,865.10/805.22
  6. Step 6: Final answer
    x = 1,031.85

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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.