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Finding the Fourth Proportional to 1,289.72, 1,780.25 and 869.80

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Solution

The fourth proportional to 1,289.72, 1,780.25 and 869.80 is: 1,200.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289.72 : 1,780.25 = 869.80 : x
  2. Step 2: Convert to fraction form
    1,289.72/1,780.25 = 869.80/x
  3. Step 3: Cross multiply
    1,289.72x = 1,780.25 × 869.80
  4. Step 4: Simplify right side
    1,289.72x = 1,548,465.85
  5. Step 5: Solve for x
    x = 1,548,465.85/1,289.72
  6. Step 6: Final answer
    x = 1,200.62

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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.