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Finding the Fourth Proportional to 1,248.50, 1,722.92 and 689

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Solution

The fourth proportional to 1,248.50, 1,722.92 and 689 is: 950.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,248.50 : 1,722.92 = 689 : x
  2. Step 2: Convert to fraction form
    1,248.50/1,722.92 = 689/x
  3. Step 3: Cross multiply
    1,248.50x = 1,722.92 × 689
  4. Step 4: Simplify right side
    1,248.50x = 1,187,091.88
  5. Step 5: Solve for x
    x = 1,187,091.88/1,248.50
  6. Step 6: Final answer
    x = 950.81

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.