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Finding the Fourth Proportional to 1,221.75, 1,686.15 and 756

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Solution

The fourth proportional to 1,221.75, 1,686.15 and 756 is: 1,043.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.75 : 1,686.15 = 756 : x
  2. Step 2: Convert to fraction form
    1,221.75/1,686.15 = 756/x
  3. Step 3: Cross multiply
    1,221.75x = 1,686.15 × 756
  4. Step 4: Simplify right side
    1,221.75x = 1,274,729.40
  5. Step 5: Solve for x
    x = 1,274,729.40/1,221.75
  6. Step 6: Final answer
    x = 1,043.36

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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.