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Finding the Fourth Proportional to 1,122.60, 1,682.86 and 861.80

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Solution

The fourth proportional to 1,122.60, 1,682.86 and 861.80 is: 1,291.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,122.60 : 1,682.86 = 861.80 : x
  2. Step 2: Convert to fraction form
    1,122.60/1,682.86 = 861.80/x
  3. Step 3: Cross multiply
    1,122.60x = 1,682.86 × 861.80
  4. Step 4: Simplify right side
    1,122.60x = 1,450,288.75
  5. Step 5: Solve for x
    x = 1,450,288.75/1,122.60
  6. Step 6: Final answer
    x = 1,291.90

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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.