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Finding the Fourth Proportional to 1,311.97, 1,809.09 and 938.80

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Solution

The fourth proportional to 1,311.97, 1,809.09 and 938.80 is: 1,294.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.97 : 1,809.09 = 938.80 : x
  2. Step 2: Convert to fraction form
    1,311.97/1,809.09 = 938.80/x
  3. Step 3: Cross multiply
    1,311.97x = 1,809.09 × 938.80
  4. Step 4: Simplify right side
    1,311.97x = 1,698,373.69
  5. Step 5: Solve for x
    x = 1,698,373.69/1,311.97
  6. Step 6: Final answer
    x = 1,294.52

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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.