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Finding the Fourth Proportional to 1,289.85, 1,780.61 and 917.61

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Solution

The fourth proportional to 1,289.85, 1,780.61 and 917.61 is: 1,266.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289.85 : 1,780.61 = 917.61 : x
  2. Step 2: Convert to fraction form
    1,289.85/1,780.61 = 917.61/x
  3. Step 3: Cross multiply
    1,289.85x = 1,780.61 × 917.61
  4. Step 4: Simplify right side
    1,289.85x = 1,633,901.09
  5. Step 5: Solve for x
    x = 1,633,901.09/1,289.85
  6. Step 6: Final answer
    x = 1,266.74

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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.