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Finding the Fourth Proportional to 1,311.91, 1,809.06 and 979.81

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Solution

The fourth proportional to 1,311.91, 1,809.06 and 979.81 is: 1,351.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.91 : 1,809.06 = 979.81 : x
  2. Step 2: Convert to fraction form
    1,311.91/1,809.06 = 979.81/x
  3. Step 3: Cross multiply
    1,311.91x = 1,809.06 × 979.81
  4. Step 4: Simplify right side
    1,311.91x = 1,772,535.08
  5. Step 5: Solve for x
    x = 1,772,535.08/1,311.91
  6. Step 6: Final answer
    x = 1,351.11

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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.