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Finding the Fourth Proportional to 1,286.70, 1,929.09 and 921.26

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Solution

The fourth proportional to 1,286.70, 1,929.09 and 921.26 is: 1,381.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,286.70 : 1,929.09 = 921.26 : x
  2. Step 2: Convert to fraction form
    1,286.70/1,929.09 = 921.26/x
  3. Step 3: Cross multiply
    1,286.70x = 1,929.09 × 921.26
  4. Step 4: Simplify right side
    1,286.70x = 1,777,193.45
  5. Step 5: Solve for x
    x = 1,777,193.45/1,286.70
  6. Step 6: Final answer
    x = 1,381.20

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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.