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Finding the Fourth Proportional to 1,389.91, 2,085.22 and 979.85

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Solution

The fourth proportional to 1,389.91, 2,085.22 and 979.85 is: 1,470.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.91 : 2,085.22 = 979.85 : x
  2. Step 2: Convert to fraction form
    1,389.91/2,085.22 = 979.85/x
  3. Step 3: Cross multiply
    1,389.91x = 2,085.22 × 979.85
  4. Step 4: Simplify right side
    1,389.91x = 2,043,194.77
  5. Step 5: Solve for x
    x = 2,043,194.77/1,389.91
  6. Step 6: Final answer
    x = 1,470.02

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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.